As noted before, J. A. Allen (1891:223) reported specimens from Rancho Santa Rosa as Ochetodon mexicanus, but he used this name for the species now known as R. fulvescens.

The specimen examined, previously reported by Jones and Anderson (1958:447), represents the northernmost occurrence of the species.

Peromyscus maniculatus blandus Osgood
Deer Mouse

1904. Peromyscus sonoriensis blandus Osgood, Proc. Biol. Soc. Washington, 17:56, March 21, type from Escalón, Chihuahua.

1909. Peromyscus maniculatus blandus Osgood, N. Amer. Fauna, 28:84, April 17.

Peromyscus melanotis J. A. Allen and Chapman
Black-eared Mouse

1897. Peromyscus melanotis J. A. Allen and Chapman, Bull. Amer. Mus. Nat. Hist., 9:203, June 16, type from Las Vigas, Veracruz.

Peromyscus leucopus texanus (Woodhouse)
White-footed Mouse

1853. Hesperomys texana Woodhouse, Proc. Acad. Nat. Sci. Philadelphia, 6:242, type probably from vicinity of Mason, Mason Co., Texas.

1909. Peromyscus leucopus texanus, Osgood, N. Amer. Fauna, 28:127, April 17.

This is the most common species of the genus Peromyscus in Tamaulipas. It and Liomys irroratus are the two rodents most easily trapped throughout the state. In general P. l. texanus occurs in forested and brushy areas especially under 1200 feet in elevation, as was noted in the Sierra de Tamaulipas, where P. l. texanus was taken commonly at elevations of up to 1200 feet. Above this elevation the species was rare and P. pectoralis and P. boylii were more abundant than at lower elevations. The three specimens of P. l. texanus from 12 kilometers north and four kilometers west of Ciudad Victoria were trapped in a line of 110 traps set near tree stumps. Small burrows in the ground were noted here. The forest at this locality was composed of mesquite, ebony, acacias, a few yuccas and "nopales" (= cactuses); the ground was covered by cat claw.

Of the many young taken, 15 specimens were saved from Ejido Santa Isabel where P. leucopus was abundant in an area of chaparral consisting of wild "tomate," "zapote," "huizache" and "salvadora." Most of the specimens caught at this locality were taken between 7:30 and 9:30 p. m. in traps baited with a mixture of rolled oats, peanut butter and banana. Specimens from 53 kilometers north of El Limón were taken along with Liomys irroratus; the specimen from two kilometers west of El Carrizo was trapped near a dead mesquite log. Reitrodontomys fulvescens was taken in the same area. Four specimens of P. leucopus were taken at Rancho Pano Ayuctle, around a big pile of old firewood in an abandoned sugar mill. At the locality six miles north and six miles west of Altamira, P. leucopus was found in cultivated fields and along the grassy roadsides; in the vicinity of Tampico specimens were taken in an area of forested cactus-thorn. The specimen from seven kilometers south and two kilometers west of San Fernando was found in a trap set at the base of "nopal" cactus, which was surrounded by bushes and small trees (10-12 feet high).

Breeding records are as follows: Rancho Pano Ayuctle, on February 15, one female carried 2 embryos of 23 mm. in crown-rump length; Jaumave, July 26 to 29, five females, averaging 4.6 (3-6) embryos of 7 (3-15) mm., two females lactating, one on May 25 and the other on July 26; Ejido Santa Isabel, on January 20 to 25, three females lactating; Soto la Marina, on May 16, one female lactating.

Average weights were as follows: from Jaumave four pregnant females, 28.0 (25-33), eight males, 23.4 (21-27); from the Sierra de Tamaulipas, eight females non-pregnant, 21.2 (18-26), 14 males, 22.0 (19-27); from 6 mi. N, 6 mi. W Altamira, six males, 23.5 (21-27).

All specimens examined from Tamaulipas are assigned to P. l. texanus because their coloration is pale. Even so the color varies some according to locality; specimens from Rancho Pano Ayuctle and the Sierra de Tamaulipas have much of the cinnamon color that is characteristic of P. l. incensus from farther south, but even so specimens from the two localities last mentioned are paler than those from Veracruz that are typical incensus.

Goldman (1942:158) reported specimens from Altamira as P. l. incensus, in which subspecies Ingles (1959:397) included specimens from two miles west of Tampico, but specimens examined from the same area do not differ from individuals from far north thereof; for this reason I identify specimens from these localities as texanus. Osgood (1909:131) and Hooper (1953:7) also referred specimens from the southern part of Tamaulipas to texanus. These two authors examined 156 specimens and did not find any intergradation between texanus and incensus, but to me, the cinnamon tones of specimens from Rancho Pano Ayuctle and the Sierra de Tamaulipas, suggest intergradation between the two subspecies.

Osgood's (1909:265) measurements of P. l. texanus, from Brownsville, Texas, and those of 40 specimens from different localities in Tamaulipas are about the same except that the anterior palatine foramina average longer in Tamaulipas. Baker's (1956:262) specimens from Coahuila, averaged larger even than Tamaulipan specimens. Another difference between Osgood's measurements and Baker's was the shorter 3.4 (3.0-3.7) maxillary tooth-row in Tamaulipan specimens.

Hooper (1953:7) recorded specimens from General Terán, as in Tamaulipas; actually this locality is in Nuevo León.

Peromyscus boylii
Brush Mouse

Specimens examined were obtained at higher elevations in the oak-tree zone of the Sierras in traps set among rocks, trees and in grassy areas. Peromyscus boylii was trapped in the same area as was P. pectoralis and no habitat distinction between the two was noted. Some behavioral differences, however, are pointed out in the account of P. pectoralis. Morphological differences between these two species in Tamaulipas were reported by Hooper (1952:372).

A female taken on August 5 in the Sierra Madre Oriental carried two embryos 15 mm. in crown-rump length.

For the taxonomic status of P. boylii in Tamaulipas see Alvarez (1961).

Peromyscus boylii ambiguus Alvarez

1961. Peromyscus boylii ambiguus Alvarez, Univ. Kansas Publ. Mus. Nat. Hist., 14:118, December 29, type from Monterrey, Nuevo León.

Peromyscus boylii levipes Merriam

1898. Peromyscus levipes Merriam, Proc. Biol. Soc. Washington, 12:123, April 30, type from Mt. Malinche, 8400 ft., Tlaxcala.

1909. Peromyscus boylii levipes, Osgood, N. Amer. Fauna, 28:153, April 17.

Weights of 19 males and 18 females from the Sierra Madre Oriental are, respectively, 25.2 (22-30) and 23.6 (20-29); weights of eight males and five females from the Sierra de Tamaulipas are 24.9 (22-32) and 29.6 (24-31).

Peromyscus pectoralis
White-ankled Mouse

Peromyscus pectoralis and P. boylii are closely related morphologically and seem to occupy the same habitat. In the Sierra Madre Oriental, according to the field notes of the collector (Heinrich, June 6 to August 5, 1953), individuals of P. pectoralis had a pinkish coloration on the mouth and forefeet produced by the juice of the "nopal" cactus fruit, on which obviously the mice feed, whereas only a few specimens of boylii were thus discolored. It was noted that boylii was feeding on acorns. Furthermore, the two species may differ in time of breeding; in August, males of pectoralis had the testes well developed when those organs were small in boylii collected at the same locality.

A specimen from 53 kilometers north of El Limón, was shot at a height of 10 feet on a concrete underpass. Other specimens were taken in a trap line that yielded Peromyscus boylii, P. leucopus and Liomys irroratus.

Two subspecies of P. pectoralis occur in Tamaulipas: P. p. collinus is widely distributed in the central and western parts of the state and P. p. eremicoides occurs only in the western "corner" of the state.

Peromyscus pectoralis collinus Hooper

1952. Peromyscus pectoralis collinus Hooper, Jour. Mamm., 33:372, August 19, type from San José, 2000 ft., Sierra San Carlos, 12 mi. NW San Carlos, Tamaulipas.

A female obtained on January 21 at a place 53 kilometers north of El Limón, contained three embryos. A lactating female was taken on August 2 in the Sierra Madre Oriental. Males, as previously noted, had well-developed testes in August. The weights of 17 males and 20 females from the Sierra de Tamaulipas were, respectively, 26.6 (24-33), and 25.6 (21-31) grams.

Measurements of specimens from different localities in Tamaulipas averaged about the same, except that those of specimens from Palmillas, averaged smaller. The small size suggests intergradation between the subspecies collinus and eremicoides. The latter occurs to the west and differs from collinus in smaller size, more grayish coloration, completely white tarsal joint and relatively longer tail. Hooper (1952:374) reported specimens from Jaumave as intergrades between the two subspecies before mentioned and Osgood (1909:164) identified two specimens from there as eremicoides. In the present account, individuals from Palmillas and Jaumave are referred to collinus.

Peromyscus pectoralis eremicoides Osgood

1904. Peromyscus attwateri eremicoides Osgood, Proc. Biol. Soc. Washington, 17:60, March 21, type from Mapimi, Durango.

1909. Peromyscus pectoralis eremicoides, Lyon and Osgood, Bull. U. S. Nat. Mus., 62:128, January 28.

The two specimens from Miquihuana are typical P. pectoralis eremicoides in external and cranial measurements. Specimens from nine miles southwest of Tula are characteristic of eremicoides in cranial measurements but the tail is shorter than usual for this subspecies, in this respect approaching P. p. lacianus.

Peromyscus melanophrys consobrinus Osgood
Plateau Mouse

1904. Peromyscus melanophrys consobrinus Osgood, Proc. Biol. Soc. Washington, 17:66, March 21, type from Berriozabal, Zacatecas.

A lactating female caught on July 20 and four males from Miquihuana weighed, respectively, 51, and 50.2 (47-54) grams. A female, taken on July 24, 14 miles north and six miles west of Palmillas in a valley covered by mesquite and other bushes, had 3 embryos 10 mm. in crown-rump length, and weighed 60 grams. One specimen from nine miles southwest of Tula was caught in an outcrop of rocks and two others were taken among bushes on the desert. A female on October 10 carried 4 embryos 2 mm. in crown-rump length.

Specimens of P. melanophrys here listed are the first to be reported from Tamaulipas. They are assigned to the subspecies consobrinus on the basis of dark color and because their size closely corresponds to that of the holotype. The specimen from the vicinity of Palmillas and one from Miquihuana (56408) are larger than the others and grayish.

A specimen (56413) from Miquihuana lacks all the molariform teeth. Its alveoli in one maxilla are closed and those in the opposite maxilla are more open than is normal.

Peromyscus difficilis petricola Hoffmeister and de la Torre
Zacatecan Deer Mouse

1959. Peromyscus difficilis petricola Hoffmeister and de la Torre, Proc. Biol. Soc. Washington, 72:167, November 4, type from 12 mi. E San Antonio de las Alazanas, 9000 ft., Coahuila.

The three specimens from Miquihuana were collected among rocks and stumps, in an oak forest. The specimens from 20 miles north of Tula were collected after midnight on a hillside covered mainly with juniper brush. A female (October 11) carried 3 embryos 26 mm. in crown-rump length.

Peromyscus ochraventer Baker
El Carrizo Deer Mouse

1951. Peromyscus ochraventer Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:213, December 15, type from 70 km. (by highway) S Ciudad Victoria, 6 km. W Pan-American Highway at El Carrizo, Tamaulipas.

The series of specimens examined was the same used by the original describer of the species. He (1951:214-215) pointed out that the mice were taken in junglelike forest among rocks and adjacent to logs. Burrows extended beneath large blocks of limestone, and each burrow where a mouse was caught was marked by a pile of excavated earth resembling a tiny mound left by a pocket gopher. These burrows were at an elevation of approximately 2800 feet above sea level on the steep sides of a small hill in an area where the vegetation was intermediate between that of the arid and humid subdivisions of the tropical region. Each of two females, captured on January 13, carried five placental scars; one of the females was lactating.

Baiomys taylori taylori (Thomas)
Northern Pygmy Mouse

1887. Hesperomys (Vesperimus) taylori Thomas, Ann. Mag. Nat. Hist., ser. 5, 19:66, January, type from San Diego, Duval Co., Texas.

1907. Baiomys taylori Mearns, U. S. Nat. Mus., Bull. 56:381, April 13.

The species of this genus have been revised recently by Packard (1960) and the specimens from Tamaulipas are arranged according to his systematic findings. The weight of 35 specimens labeled with reference to Altamira are 7.6 (6.0-9.0) grams; 15 from Jaumave weigh 6.9 (6.0-9.0) grams. Pregnant females were collected as follows: February 22, Ejido Santa Isabel, 3 (embryos x 4 mm. in crown-rump length); March 2, Rancho Pano Ayuctle, 6 x 16; July 9, six miles north and six miles west of Altamira, 1 x 4; July 28 and 29, Jaumave, 2 x 8 and 3 x 9. The average number of embryos was 2.8 (1-5).

Onychomys leucogaster longipes Merriam
Northern Grasshopper Mouse

1889. Onychomys longipes Merriam, N. Amer. Fauna, 2:1, October 30, type from Concho County, Texas.

1913. Onychomys leucogaster longipes, Hollister, Proc. Biol. Soc. Washington, 26:216, December 20.

Only a young female was examined; she weighed 22 grams and extends the known range 59 miles eastward from Ciudad Victoria.

Onychomys torridus subrufus Hollister
Southern Grasshopper Mouse

1914. Onychomys torridus subrufus Hollister, Proc. U. S. Nat. Mus., 47:472, October 29, type from Miquihuana, Tamaulipas.

The six specimens examined were collected in the desert area west of the Sierra Madre Oriental. At Nicolás a trap set in front of a hole held one specimen, and another was trapped beneath a brush fence that inclosed a cornfield. Dipodomys merriami and Perognathus penicillatus also were trapped beneath the fence.

A subadult from Nicolás is slightly larger (see measurements) than either of two subadults from four miles north of Jaumave and an old specimen from eight miles north of Tula, except in the interorbital constriction, which is narrower. Nevertheless measurements of Tamaulipan Onychomys torridus resemble those given by Hollister (1914:483) for O. t. subrufus. A specimen from Nicolás is also darker than other individuals examined.

A female taken on July 15, four miles north of Jaumave, was lactating.

Sigmodon hispidus
Hispid Cotton Rat

This species, as is known, is active by day and by night. It occurs mainly in grassy areas and most of the specimens examined were trapped there. But, one mile east of La Pesca, specimens were taken on a beach having sparse grass. Neotoma micropus and Spermophilus spilosoma, but no smaller rodents, were taken there. Also, many crabs were found in the traps. Possibly only the relatively large rodents are able to compete successfully with the crabs. The specimen from one kilometer east of El Barretal was caught in a rat-trap set in front of small hole in a fence of dead brush that surrounded a cornfield. The area outside the fence supported mesquite and ebony trees (10-12 feet high) and the ground was covered with cat claw. Six miles north and six miles west of Altamira, the two young specimens were taken on a small grassy island surrounded by mud.

According to natives, Sigmodon injures corn and sugar cane. Probably other species of rodents are responsible for some or all of such damage since other kinds of rodents were taken in the same areas.

Dice (1937:245) reported females from the Sierra San Carlos that carried 8 embryos of 18 mm., 5 × 33, 7 embryos very small, and 8 × 20. Females were collected on July 22, 29, and 30.

Sigmodon hispidus berlandieri Baird

1855. Sigmodon berlandieri Baird, Proc. Acad. Nat. Sci. Philadelphia, 7:333, type from Río Nazas, Coahuila.

1902. Sigmodon hispidus berlandieri, V. Bailey, Proc. Biol. Soc. Washington, 15:106, June 2.

This subspecies is distinguished from S. h. toltecus by larger size and paler, grayish coloration.

Table 3.—Data on Reproduction.

Baker (1951:216) reported a specimen from 35 kilometers north and 10 kilometers west of Ciudad Victoria (= 1 km. E El Barretal) as S. h. toltecus. Comparison of its skull with those from the vicinity of Altamira (S. h. toltecus) and those from Jaumave (S. h. berlandieri) shows that the skull from El Barretal closely resembles those from Jaumave, in having the zygomatic arches more nearly parallel and the braincase more rounded than in skulls from Altamira. Therefore the specimen from the vicinity of El Barretal is here assigned to S. h. berlandieri.

Sigmodon hispidus solus Hall

1951. Sigmodon hispidus solus Hall, Univ. Kansas Publ., Mus. Nat. Hist., 5:42, October 1, type from island 88 mi. S, 10 mi. W Matamoros, Tamaulipas.

Sigmodon hispidus toltecus (Saussure)

1860. [Hesperomys] toltecus Saussure, Revue et Mag. Zool., Paris, ser. 2, 12:98, type from mountains of Veracruz [probably near Mirador, Dalquest, Louisiana State Univ. Studies, Biol. Sci. Series, 1:163, December 28, 1953].

1902. Sigmodon hispidus toltecus, V. Bailey, Proc. Biol. Soc. Washington, 15:110, June 2.

Neotoma albigula subsolana Alvarez
White-throated Woodrat

1962. Neotoma albigula subsolana Alvarez, Univ. Kansas Publ. Mus. Nat. Hist., 14:141, April 30, type from Miquihuana, 6400 ft., Tamaulipas.

At Nicolás specimens were taken in traps set along a thorn fence and at Tajada two specimens were trapped along a rock wall. At other places some specimens were brought in by natives who captured the rats by tearing apart their houses.

Five females taken on October 18 at Nicolás carried embryos (one to two per female), which averaged 22.2 (11-45) mm. in crown-rump length. Another female, taken nine miles southwest of Tula on October 13, carried 2 embryos that were 35 mm. in crown-rump length. The average weight of the five pregnant females was 196.7 (183-207) grams. The average weights of nine adult males and six non-pregnant females from Miquihuana were, respectively, 215.6 (175-250) and 162.5 (155-175) grams.

Neotoma angustapalata Baker
Tamaulipas Wood Rat

1951. Neotoma angustapalata Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:217, December 15, type from 70 km. by highway S Ciudad Victoria, and 6 km. W Pan-American highway at El Carrizo, Tamaulipas.

Baker (1951:218) reported that specimens from the type locality were taken in crevices among rocks on a small hillside that supported a sparse cover of vegetation growing from a deep layer of humus. The specimen from eight kilometers west and 10 kilometers north of El Encino was shot about 40 yards from the entrance to a large cave, but no sign of wood rats were found there. Hooper (1953:9) reported that N. angustapalata occupied caves at Rancho del Cielo, where a female with two nursing young was taken.

When Baker (op. cit.) described Neotoma angustapalata on the basis of two specimens from El Carrizo, he assigned the species to the N. mexicana group because of the deep anterointernal re-entrant angle of M1. The deep angle found in N. mexicana differs markedly from the typical condition in either N. micropus or N. albigula. Study of the cranial characters and bacula of specimens of N. micropus and N. angustapalata tends to corroborate the statement of Hooper (1953:10), who commented on the taxonomic relationships of N. angustapalata as follows: "It should be pointed out that all characters considered ... the specimens [angustapalata] appear to be large, deeply pigmented examples of the species N. micropus notwithstanding the deep anterior fold in M1. The presence of that deep fold is far from an absolute character in the mexicanus [sic] group."

My study of 48 crania of N. micropus from Tamaulipas reveals that the depth of the re-entrant angle of M1 is extremely variable, from almost absent in some individuals to deep (as in angustapalata) in others. Four specimens, one (56958) from the Sierra de Tamaulipas and three (56960, 56965, 56966) from the vicinity of Altamira, have the re-entrant angle as deep as in the holotype and topotype of angustapalata.

Comparison of the bacula of the holotype and one topotype of angustapalata with 15 bacula of N. micropus reveal that on the average the baculum of angustapalata differs from that of micropus in being longer, and narrower at the base (greatest length, 7.1, width at base, 3.4 mm., in the topotype). One specimen of N. micropus littoralis from the vicinity of Altamira, however, has a baculum of the same shape as in angustapalata (this same specimen is one of the three from there in which the re-entrant angle of the M1 is deep). The shape of the baculum among specimens of micropus is highly variable and bacula of specimens from different localities frequently are slightly different (see Fig. 5).

The known distributions of N. micropus and N. angustapalata do not overlap (neither does the distribution of N. albigula overlap with either in Tamaulipas). The four specimens of N. micropus having the deep re-entrant angle in M1 are from localities near where the ranges of angustapalata and micropus probably meet. This could be interpreted in two ways: (1) these four specimens can be regarded as intergrades between angustapalata and micropus, in which case the former species should be placed as a subspecies of the latter. Or the four specimens, which were collected along with other specimens that lack deep re-entrant angles in the M1, can be assigned, on the basis of the deep angle, to angustapalata, in which case the species micropus and angustapalata would be in part sympatric. Until more material from critical areas is available for study, I continue to recognize angustapalata as a monotypic species. I agree with Hooper that it is closely related to N. micropus.

Neotoma micropus
Southern Plains Wood Rat

Most of the specimens examined were trapped in brushy areas. On the Sierra de Tamaulipas, wood rats were caught in steel traps set near or between rocks. In the vicinity of La Pesca, specimens were trapped on the beach where Spermophilus spilosoma and Sigmodon hispidus were taken also.

Two females, obtained on May 19 and June 10 at Soto la Marina and on the Sierra de Tamaulipas, respectively, each carried 2 embryos that were 40 mm. in crown-rump length. Dice (1937:254) reported that two females collected on July 24 and August 16 on the Sierra San Carlos each carried 2 embryos that ranged from 34 to 36 mm. in crown-rump length.

Neotoma micropus occurs throughout the Tamaulipan Biotic Province and is represented in Tamaulipas by two subspecies, each of which has its type locality in the state. Intergradation between the two takes place at Soto la Marina.

Neotoma micropus littoralis Goldman

1905. Neotoma micropus littoralis Goldman, Proc. Biol. Soc. Washington, 18:31, February 2, type from Altamira, 100 ft., Tamaulipas.

Weight of two males and three non-pregnant females was 248, 254, 185, 210, 240 grams, respectively.

Neotoma micropus micropus Baird

1855. Neotoma micropus Baird, Proc. Acad. Nat. Sci. Philadelphia, 7:333, April, type from Charco Escondido, Tamaulipas.

The weight of five males and four females from Soto la Marina averaged, respectively, 256.4 (210-317) and 233.0 (195-274) grams.

A specimen (56924) from La Pesca differs from all other specimens of N. micropus examined in being smaller, having a conspicuously shorter rostrum, broader intraorbital canal, and lower broader braincase. External measurements of this specimen are as follows: 347; 155; 39; —. Its cranial measurements are: greatest length, 44.8; basilar length, 34.3; zygomatic breadth, 23.6; interorbital constriction, 6.2; incisive foramina, 6.5; length of maxillary tooth-row, 8.7; width of mesopterygoid fossa, 4.1.

Microtus mexicanus subsimus Goldman
Mexican Vole

1938. Microtus mexicanus subsimus Goldman, Jour. Mamm., 19:494, November 14, type from Sierra Guadalupe, southeastern Coahuila.

Canis latrans
Coyote

In Tamaulipas two and possibly three subspecies of Canis latrans occur. C. l. texensis is known only from the northwesternmost part of the state, and C. l. microdon occurs from Camargo south to Nicolás. Hall and Kelson (1959:845) guessed that C. l. cagottis would be found in the southern third of the state; as yet specimens from there have not been obtained and the subspecific identity of the coyotes there, if any are present, remains in doubt.

Canis latrans microdon Merriam

1897. Canis microdon Merriam, Proc. Biol. Soc. Washington, 11:29, March 15, type from Mier, on Río Grande, Tamaulipas.

1932. Canis latrans microdon, Nelson, Proc. Biol. Soc. Washington, 45:224, November 26.