NAVICULA ANGLICA RALFS
Valve elliptical, with sub-capitate or rostrate ends; axial area narrow, central area small; striæ radiate, 12-13 in 10 µ, distinctly punctate. L. 26 µ.
Fresh water.
Pl. 26, Fig. 26.
NAVICULA GASTRUM EHR.
Valve elliptical, with rostrate ends; axial area narrow, central area transverse or irregular; striæ radiate, 9 in 10 µ in the middle. L. 26 µ.
The form here figured approaches N. anglica.
Kirkwood Pond, N. J.
Pl. 26, Fig. 25.
NAVICULA DICEPHALA WM. SM.
Valve linear, with rostrate or rostrate-capitate ends; axial area narrow, central area rectangular, transverse; striæ radiate, 12 in 10 µ. L. 32 µ.
Fresh water.
Pl. 27, Fig. 16.
NAVICULA HUMILIS DONK.
Valve elliptical, with broad, rostrate ends; axial area narrow; central area small; striæ radiate and distant in the middle, convergent at the ends, coarse, appearing costate, averaging 9 in 10 µ. L. 19 µ. As Donkin states, the striæ are "very conspicuous."
Navicula hungarica var. capitata (Ehr.) Cl.
Navicula globiceps Lagerstedt, according to Cleve.
Willistown, Pa.
Pl. 27, Fig. 24.
NAVICULA PINNATA PANT. ?
Valve lanceolate, obtuse; axial area narrow, widened in the middle; striæ coarse, 7 in 10 µ in the middle, radiate, 10 in 10 µ at the ends and transverse, indistinctly lineate. L. 40 µ.
Near Navicula ardua Mann (Diat. Albatross Voy., Cont. U. S. Nat. Herbarium Vol. 10, Part 5, p. 336, Pl. 53, Fig. 2) which, however, is said to have "strictly unbeaded costæ."
Pavonia, N. J., artesian well.
Pl. 27, Fig. 20.
NAVICULA PENNATA A. S.
Valve lanceolate, acute; axial area narrow; central area quadrate, transverse; striæ radiate, coarse, 5 in 10 µ, lineate. L. 68-95 µ (Cleve).
Pavonia, N. J., artesian well.
Pl. 27, Fig. 22.
NAVICULA INFLEXA GREG.
Valve slightly elliptical-lanceolate, sub-acute, smooth at the ends; axial area narrow, widened in the middle; striæ radiate, 11 in 10 µ, lineate. Frustule in zone view constricted in the middle. L. 28-45 µ.
Common along the coast.
Pl. 27, Figs. 18 and 19.
NAVICULA OBLONGA KUETZ.
Valve linear-lanceolate, with broad, rounded ends; margin sometimes undulate; axial area narrow; central area large, orbicular; striæ in the middle distant, radiate, convergent at the ends and curved or sharply bent, 7 in 10 µ, lineate. L. 70-200 µ (Cleve).
Blue clay. Occasional in fresh water.
Pl. 27, Fig. 21.
NAVICULA HASTA PANT.
Valve lanceolate, gently tapering to the obtuse, produced ends; axial area lanceolate, widened to an orbicular space in the middle; striæ radiate, the median coarse and quite distant, 5 in 10 µ, becoming closer at the ends where they are 12 in 10 µ, lineate. The distance between the median striæ gives the appearance of a stauros.
Occasional in the blue clay.
Pl. 27, Fig. 13.
NAVICULA HASTA VAR. PUNCTATA N. VAR.
Valve as in type but with striæ in the middle distinctly punctate and reaching the median line.
Greenwich Point, Philadelphia.
Pl. 27, Fig. 14.
NAVICULA RHYNCOCEPHALA KUETZ.
Valve lanceolate, with produced ends; axial area indistinct; central area small, rounded; striæ radiate in the middle, convergent at the ends, 10-11 in 10 µ, punctate. L. 42 µ.
Fresh water. Common.
Pl. 31, Fig. 8.
NAVICULA CRYPTOCEPHALA KUETZ.
Valve lanceolate, with rostrate ends; axial area indistinct; central area small; striæ, 16 in 10 µ, lineate, radiate in the middle, convergent at the ends. L. 28 µ.
Common in fresh water.
Intermediate forms occur between N. rhyncocephala and N. cryptocephala.
Pl. 31, Fig. 9.
NAVICULA LONGA (GREG.) RALFS
Valve slender, rhombic, elongated, with acute ends; axial area indistinct; central area small; striæ, 6 or 7 in 10 µ, radiate in the middle, elsewhere transverse; central pores closely approximate. L. 120 µ.
New Rochelle, N. Y.
Pl. 31, Fig. 10.
Cleve refers this form to N. directa var. remota Grun. Some specimens are found in this locality showing the "generally twisted" median line mentioned by Gregory.
Mesoleiæ Cl.
Valve linear or elliptical; axial area narrow; central area quadrate; striæ radiate, finely punctate.
NAVICULA MUTICA KUETZ.
Valve ovate, elliptical or lanceolate; axial area narrow; central area dilated into a stauros not reaching the margin; striæ about 20 in 10 µ, more distant in the middle, radiate, punctate. A punctum occurs on one side of the central nodule.
Reported from New Jersey in fresh water. I have not found it. The figure is from a specimen from another locality.
Pl. 26, Fig. 6.
NAVICULA MINIMA GRUN.
Valve broadly elliptical, 13-15 µ in length; axial area narrow; central area small but with a quadrate pseudo-stauros which is striated; striæ, about 28 in 10 µ, radiate.
Agrees closely with N. saugeri var. Grun. in V. H. Synopsis, Pl. 14, Fig. 16, said to be intermediate between N. minima and N. atomoides Grun. N. minima var. atomoides Grun. is smaller.
Common in water-troughs.
Pl. 26, Fig. 13.
NAVICULA PUPULA VAR. BACILLARIOIDES GRUN.
Valve linear, with rounded ends; axial area linear, expanding on both sides near the ends of the valve, forming a transverse lunate space; central area small, apparently expanded into a stauros, which, however, is striated; striæ, 18 in 10 µ, at the middle, closer at the ends, punctate. L. 54 µ.
Pavonia, N. J., artesian well.
Pl. 26, Fig. 9.
Bacillares Cl.
Valve linear or linear-elliptical, with broad ends; axial area narrow, the median line enclosed in siliceous ribs; striæ finely punctate, more distant in the middle.
NAVICULA BACILLUM EHR.
Valve linear, with rounded ends; axial area enclosed in siliceous ribs and slightly expanded on each side at the ends; terminal nodules incrassate; central area small, elliptical; striæ, 15 in 10 µ in the middle, transverse, distinctly punctate, closer at the ends L. 47 µ.
Fresh water.
Pl. 26, Fig. 10.
Cleve describes the form as having slightly radiate striæ in the middle. There is considerable difference in the descriptions of Cleve, Donkin, Grunow and Van Heurck, as also in all of the figures.
NAVICULA AMERICANA EHR.
Valve oblong-linear, with rounded ends, sometimes slightly constricted; axial area about one-half the width of the valve, dilated in the middle; striæ parallel in the middle, radiate at the ends, 15-16 in 10 µ. A punctum is usually found in the central nodule. L. 55-154 µ.
Blue clay. Occasional in fresh water.
Pl. 26, Fig. 8.
Decipientes Cl.
Valve lanceolate, with obtuse ends; axial area narrow; central area orbicular; striæ radiate in the middle and more distant.
NAVICULA SEMEN EHR.
Valve elliptic-lanceolate, with sub-rostrate, truncate apices; axial area narrow, sinuous; central area orbicular; terminal fissures small, hook-shaped; striæ robust, 7 or 8 in the middle, closer at the ends, indistinctly punctate or lineolate.
Blue clay. Not common.
Pl. 26, Fig. 11.
Cleve states that this form belongs to the post-glacial deposits and is found living only in the Hartz Mountains.
NAVICULA INTEGRA WM. SM.
Valve lanceolate with triundulate margins and rostrate-apiculate ends; striæ radiate, more distant in the middle, 20-23 in µ, punctate; axial area very narrow, central area rounded or elliptical. L. 33-43 µ.
Pavonia, N. J., artesian well. Common in Chester River, Md.
Pl. 26, Fig. 5.
Microstigmaticæ CL.
Valve lanceolate; axial area narrow; central area small, rounded; striæ finely punctate, nearly parallel. (Includes here only the division Libellus.)
NAVICULA TUMIDA (BRÉB.) CL.
Valve lanceolate, with rounded ends; axial area narrow, central area elliptical; raphe slightly sigmoid; striæ, 13 in 10 µ, finely punctate, a few shorter in the middle.
Scoliopleura tumida (Bréb.) V. H.
Cape May, N. J.
Pl. 25, Fig. 1.
NAVICULA GREVILLEI (AG.) CL.
Frustules in gelatinous tubes, rectangular; zone with numerous longitudinal divisions. Valve elliptical-lanceolate, obtuse; axial area narrow, central area small; striæ lineate, about 18 in 10 µ in the middle where they are slightly radiate and more evident, closer near the ends and transverse; median line with terminal pores distant from the ends. L. 60 µ.
Schizonema grevillei Ag.
East River, N. Y.
Pl. 31, Figs. 3 and 4.
NAVICULA LIBELLUS GREG.
Valve rhombic-elliptical, obtuse at the ends; axial area narrow, central rounded, small; striæ punctate, slightly radiate, about 19 in 10 µ; terminal fissures close to the ends, indistinct. L. 60 µ.
Cleve describes this form as having acute ends, while Gregory states that it is "more obtuse and broader than N. rhombica." Gregory's Figure 101 apparently shows the ends acute, but he says that the valve view is "rhombic or elliptic-lanceolate, broad, with obtuse ends" (Diat. of the Clyde, p. 57, Pl. 6).
Hackensack Swamp, N. J.
Pl. 31, Fig. 5.
Orthostichæ Cl.
Valve lanceolate or elongated; axial area narrow; central area sometimes apparently dilated into a stauros; striæ punctate, the puncta in transverse and longitudinal rows.
NAVICULA CUSPIDATA KUETZ.
Valve rhombic-lanceolate, with acute ends; axial area linear, narrow, not widened in the middle; striæ transverse, 14-19 in 10 µ (Cl.). L. 70-150 µ.
Blue clay. Not uncommon in fresh water.
Pl. 26, Figs. 1 and 2.
Fig. 2 represents an inner valve or stratum, with strong costæ variable in size, formerly known as Surirella craticula Ehr.
N. cuspidata var. ambigua (Ehr.) Cl.—Valve elliptical-lanceolate, with rostrate ends, smaller than the type and with finer striæ.
Crum Creek.
Pl. 26, Fig. 3.
NAVICULA SPICULA (HICKIE) CL.
Valve narrow, lanceolate with acute ends; axial area narrow, central area dilated into a stauros reaching the margin; transverse striæ, 25-29 in 10 µ, longitudinal closer. L. 50-130 (Cl.).
Sometimes confused with N. crucigera.
Stauroneis spicula Hickie.
Newark, N. J.
Pl. 26, Fig. 4.
NAVICULA CRUCIGERA (WM. SM.) CL.
Valve lanceolate, narrow, with acute apices; central nodule a stauros reaching the margin but crossed by two or three coarser striæ; transverse striæ, 12 in 10 µ, punctate, the puncta about 25 in 10 µ. L. 80-100 µ (Cl.). Frustules in gelatinous tubes or free.
Schizonema cruciger Wm. Sm.
Pl. 26, Fig. 15.
Reported as occurring in New York Bay, but I have not seen it. The figure is from a specimen from another locality.
Minusculæ Cl.
Valve lanceolate or elliptical, chiefly distinguished by the small size; axial area indistinct; central area small; striæ radiate, very finely punctate.
NAVICULA ATOMUS NÆGELI
Valve elliptical, 6-8 µ in length; striæ radiate, 26-30 µ, closer near the ends; axial area linear, scarcely widened in the middle.
Water-troughs and ditches. Probably common, but frequently not noticed because of its minuteness. A mounting medium of the highest refractive index, such as realgar, is required to resolve the striæ. In the figure the striæ are drawn a little coarser than they appear in most specimens.
Pl. 26, Fig. 12.
Lævistriatæ Cl.
Valve lanceolate, axial area distinct; central area orbicular; striæ coarse, indistinctly punctate, approaching the costæ of Pinnularia.
NAVICULA YARRENSIS GRUN.
Valve elliptical-lanceolate, with rounded ends; axial area lanceolate, widened in the middle; striæ, 5 in 10 µ. L. 97 µ.
Cape May, N. J. Common.
Pl. 25, Fig. 14.
Fig. 15, a smaller form, 65 µ in length; striæ, 6 in 10 µ.
Fig. 16, 54 µ in length; striæ, 8 in 10 µ (near var. valida Pant.).
NAVICULA ELEGANS WM. SM.
Valve elliptical-lanceolate, with produced ends; axial area very narrow, central area large, orbicular; striæ strongly divergent in the middle, slightly, if at all, convergent at the ends, curved toward the margin, indistinctly lineate, 9 in 10 µ. L. 95 µ.
Blue clay. Not rare.
Pl. 31, Fig. 1.
Navicula elegans var. cuspidata Cl.—Valve as in type form but smaller and with rostrate apices; striæ, 10 in 10 µ. L. 82 µ.
Belmar, N. J.
Pl. 31, Fig. 2.
Cleve remarks that the type form is acute and the striæ 9, while the var. cuspidata has 12 striæ in 10 µ. In Fig. 1, Pl. 31, is represented a valve having 9 striæ in 10 µ, but not acute, while Fig. 2, with but slight variation in striæ, is more cuspidate. It is probable there are intermediate variations.
NAVICULA PALPEBRALIS BRÉB.
Valve elliptical-lanceolate, with acute apiculate ends; axial area broad, lanceolate; striæ radiate, lineate, about 11 in 10 µ. L. 60 µ.
Along the coast.
Pl. 31, Figs. 6 and 7.
On Plate 40, Fig. 5, is represented an abnormal form of Navicula in which the central pores are in a line transverse to the longitudinal axis and each raphe is curved in a line which almost returns to the centre. The puncta are in curved lines radiating from the rounded hyaline centre.
Pavonia, N. J., artesian well.
Weissflog has described valves of Navicula somewhat similar in punctation.
(pinnula, a small feather)
Valve linear or nearly so, with rounded ends; axial area broad; central and terminal areas large; costæ smooth, transverse or radiating, usually convergent at the ends.
The costæ are channels on the inside of the valve, closed, except in the middle where elliptical foramina, opening into the interior of the valve, give rise through their terminal margins to the two longitudinal lines on each side of the valve. The raphe begins as a groove in the side of the conical central nodule and continues as a cleft at right angles to the plane of the surface of the valve, in which case the raphe forms a single line; if the raphe is inclined to the valve surface, then two lines appear in projection, the upper and lower edges of the cleft. In some forms the surface of the edge of the raphe on one side is folded or grooved for a considerable distance, and the opposite edge is elevated into a ridge or tongue fitting into the groove. In such cases it is possible, in projection, to see the upper or outer edges of the raphe, the lower edges and the edges of the tongue and groove, thus showing four lines; sometimes, when the tongue and groove do not meet, six lines. The so-called inner channel is the part of the raphe on the inside of the tongue, and the so-called exterior channel is the part of the raphe on the outside of the tongue. If, in addition to this formation of the raphe, the plane of cleavage changes toward the terminal nodules, the lines will cross each other and, when two are superimposed, disappear altogether. For the careful examination of the raphe it is necessary to employ large forms, and it is advisable to use nitrate of silver which remains in the raphe, and, as in slides mounted by Mr. F. J. Keeley, shows in a beautiful manner the entire outline of raphe and fissures. The terminal fissures owe their separation to the different directions taken by the two edges of the raphe on each side, one edge bending in a wide curve toward the end of the valve, showing two lines, the upper and lower edges of one side of the raphe when inclined to the plane of the surface, and the other edge of the raphe turning suddenly in an opposite direction and ending abruptly in a curve, giving rise to the appearance, by diffraction, of a punctum.
Pl. 40, Figs. 13, 14 and 15.
Endochrome consists of two chromatophores lying on the zones.
Pinnularia is usually divided into the Majores, or larger, and the Minores, or smaller forms, the latter being further divided according to their striæ. The following classification is chiefly that of Cleve.
Majores.—Valve large, linear with parallel or slightly radiate striæ and broad axial area.
Gracillimæ.—Valve small, striæ parallel or nearly so; axial area very narrow.
Capitatæ.—Valve with capitate or rostrate ends; striæ radiate.
Divergentes.—Striæ strongly radiate.
Brevistriatæ.—Striæ short.
Distantes.—Striæ distant.
Tabellariæ.—Striæ radiate in the middle, strongly convergent at the ends.
Marinæ.—Marine forms.
Majores
PINNULARIA MAJOR (KUETZ.) WM. SM.
Valve linear, usually slightly gibbous in the middle and at the ends; raphe oblique; axial area less than one-third the width of valve, convergent at the ends; striæ, 7 or 8 in 10 µ, radiate in the middle, convergent at the ends, crossed by a narrow band. L. ? to 300 µ.
Blue clay. Fresh water. Abundant at Middletown, Delaware Co. (T. C. Palmer).
Pl. 28, Fig. 4.
Fig. 9, Pl. 29, is one of a number of smaller forms which are difficult to determine, approaching P. viridis.
PINNULARIA MAJOR VAR. PULCHELLA N. VAR.
Valve strongly gibbous in the middle and gradually widened to the rounded ends; axial area broad, less than one-third the width of the valve, widened unilaterally in the middle; striæ, 7 in 10 µ, crossed by a band nearly as wide as the length of the costæ and scarcely distinct. L. 273 µ.
The central nodule is scarcely evident, probably because it is not so thick as in other forms. The outline is near to that of N. mesogongyla and certain forms of N. nobilis, differing from the latter in the median line, striæ and band which is wider than that of P. latevittata var. domingensis Cl.
Hammonton Pond, N. J.
Pl. 28, Fig. 2.
A very beautiful form which I cannot find described or figured. It does not appear to be N. major var. turgidula Cl., which has a narrow band. In the fossil deposit from Hopkinton, N. H., valves occur similar in outline but smaller.
PINNULARIA NOBILIS EHR.
Valve slightly gibbous in the middle and at the ends; median line complex; striæ, 4 or 5 in 10 µ, slightly convergent or parallel at the ends, crossed by a band one-third as wide as the length of the striæ. L. ? to 350 µ.
Blue clay. Fresh water.
Pl. 28, Fig. 1.
PINNULARIA DACTYLUS EHR.
Valve broad, linear, slightly gibbous in the middle; ends broad, rounded; median line not complex, sinuous; striæ, 4 or 5 in 10 µ, crossed by a very broad band. L. ? to 300 µ.
Navicula gigas A. S.
Blue clay. Fresh water.
Pl. 28, Fig. 3.
Forms occur which are with difficulty assigned to either nobilis or dactylus.
PINNULARIA DACTYLUS VAR. DARIANA (A. S.) CL.
Valve linear-lanceolate, obtuse; axial area broad, less than one-third the width of the valve; striæ, 6 in 10 µ, crossed by a broad band. L. 220 µ.
Absecon, N. J.
Pl. 29, Fig. 3.
PINNULARIA DACTYLUS VAR. DEMERARÆ CL.
Valve elliptical-lanceolate, with sub-cuneate ends; axial area lanceolate, broad in the middle; median line flexuose; striæ radiate throughout, 6 in 10 µ. L. 150 µ.
Blue clay.
Pl. 29, Fig. 10.
PINNULARIA GENTILIS (DONK.) CL.
Valve linear, with rounded ends; axial area about one-fourth the diameter of the valve; striæ radiate in the middle, convergent at the ends, 7 in 10 µ, crossed by a broad indistinct band.
Fresh water. Not common.
Pl. 29, Fig. 1.
PINNULARIA TRIGONOCEPHALA CL.
Valve linear, gibbous in the middle and at the cuneate ends; axial area wider between the middle and the ends, dilated to an elliptical space in the middle; striæ, 6 in 10 µ. L. 145 µ.
Blue clay.
Pl. 29, Fig. 8.
PINNULARIA VIRIDIS NITZSCH
Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle; striæ, 6 to 7 in 10 µ, crossed by a band as wide as one-third the length of the striæ.
Common in fresh water.
Pl. 29, Fig. 2.
Quite variable in size. Approaches P. major by intermediate forms as in Fig. 9, Pl. 29.
PINNULARIA VIRIDIS VAR. FALLAX CL.
Valve linear, with rounded ends; axial area narrow, slightly widened in the middle; striæ sometimes unilaterally interrupted, nearly parallel, 10 in 10 µ.
Elm, N. J.
Pl. 29, Fig. 4.
In Fig. 2, Pl. 30, a form is represented which corresponds closely to Navicula viridis var. B, of Wm. Smith. It is given as synonymous with var. fallax; it is bilaterally interrupted. Blue clay.
PINNULARIA VIRIDIS VAR. ?
Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle to a transverse fascia which is sometimes unilateral; striæ, 14, in the middle, divergent, convergent at the ends and closer, crossed by a narrow band. L. 45-60 µ. Fascia sometimes absent or very narrow.
Northbrook, Pa.
Pl. 30, Fig. 17 (represents a form with wider area than usual).
PINNULARIA VIRIDIS VAR. CAUDATA N. VAR.
Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, widened to an orbicular space in the middle; striæ radiate in the middle, 11-12 in 10 µ, convergent and closer at the ends, crossed by a narrow band; median line with very long terminal fissures; terminal nodules noticeable because of the thickening of the edges of the terminal striæ. L. 43 µ.
Fresh water, Newtown Square. Not common.
Pl. 30, Fig. 18.
PINNULARIA SOCIALIS (PALMER)
Valve linear, with rounded ends; axial area broad, one-third the width of the valve; striæ slightly radiate in the middle, convergent at the ends, elsewhere parallel, 8 in 10 µ, crossed by an indistinct band about one-third the length of the striæ. L. 60-120 µ.
This species, discovered by Mr. Palmer near Media, Pa., is remarkable for the grouping of the frustules "held with girdle sides together by a siliceous cementing of valve edges and enclosed in a common coleoderm." The usual number included in a group is four, but sometimes six or eight are noticed. The frustules adhere near their ends and are so firmly fastened that boiling in nitric acid and bichromate of potash for fifteen minutes will not separate them.
Navicula socialis Palmer (Proc. Acad. Nat. Sci., Phila., 1910, p. 460, Pl. 35).
Media, Pa.
Pl. 29, Fig. 5.
PINNULARIA ÆSTUARII CL.
Valve linear, with rounded ends; axial area broad, less than one-third the width of the valve; central area a transverse fascia; striæ, 7 in 10 µ, parallel except at the ends where they are slightly convergent; median line flexuose, with short, terminal semicircular fissures. L. 85 µ.
Port Penn, Delaware River. Rare.
Pl. 29, Fig. 6.
Gracillimæ
PINNULARIA MOLARIS (GRUN.) CL.
Valve very convex, linear, with sub-cuneate ends; axial area narrow, expanded in the middle to a transverse fascia reaching the margin; striæ divergent in the middle, convergent at the ends, 16 in 10 µ. L. 60 µ.
Fresh water.
Pl. 29, Fig. 15.
PINNULARIA LEPTOSOMA GRUN.
Valve linear, rounded at the ends; axial area narrow; central area a broad transverse fascia; striæ slightly divergent in the middle and convergent at the ends, 17 in 10 µ in the middle, closer at the ends. L. 56 µ.
Fresh water. Not common.
Pl. 30, Fig. 10.
Capitatæ
PINNULARIA MESOLEPTA EHR.
Valve linear, with triundulate margins and capitate ends; axial area narrow, widened in the middle; striæ divergent in the middle, convergent at the ends, about 12 in 10 µ. L. 34 µ.
Common in fresh water.
Pl. 29, Fig. 13.
PINNULARIA MESOLEPTA VAR. STAURONEIFORMIS GRUN.
Valve triundulate, capitate; axial area narrow, widened in the middle to a transverse fascia, broader at the margin; striæ strongly divergent in the middle and convergent at the ends, 9-10 in 10 µ. L. 70 µ.
Pavonia, N. J., artesian well. Fresh water.
Pl. 30, Fig. 20.
PINNULARIA SUBCAPITATA GREG.
Valve linear or linear-elliptical, with sub-capitate ends; axial area distinct, widened to a transverse fascia in the middle; striæ divergent in the middle, convergent at the ends, 13 in 10 µ. L. 32 µ.
Fresh water.
Pl. 29, Fig. 20.
PINNULARIA SUBCAPITATA VAR. PAUCISTRIATA GRUN.
Valve linear-elliptical, with rounded ends; axial area gradually widened into a broad, transverse fascia; striæ divergent in the middle, convergent at the ends, 11-12 in 10 µ. L. 47 µ.
Fresh water.
Pl. 30, Fig. 16.
PINNULARIA TERMES (EHR.) A. S.
Valve linear, with concave margins and rostrate-capitate ends; axial area narrow, widened in the middle to an orbicular or sub-quadrate space; striæ divergent in the middle, scarcely, if at all, convergent at the ends, 10 in 10 µ.
Pensauken, N. J., artesian well.
Pl. 29, Fig. 17.
This is, I believe, the form figured by Schmidt (Atlas, Pl. 45, Fig. 67). Cleve refers it to Pinnularia interrupta forma biceps, in which the central space is rhomboid.
PINNULARIA TERMES VAR. STAURONEIFORMIS V. H.
Valve linear, with concave margins and capitate-rostrate ends; axial area narrow, widened into a rhomboidal fascia, reaching the margin; striæ, 10 in 10 µ, divergent in the middle, convergent at the ends.
Pinnularia interrupta forma stauroneiformis Cl.
Fresh water.
Pl. 29, Fig. 14.
PINNULARIA APPENDICULATA (AG.) CL.
Valve linear, with subcapitate ends; axial area narrow; central area a transverse fascia; striæ divergent in the middle, convergent at the ends, 16 in 10 µ. L. 43 µ.
Fresh water. Marl pits, Lenola, N. J. (Palmer).
Pl. 29, Fig. 18.
PINNULARIA BRAUNII GRUN.
Valve linear-lanceolate, with capitate ends; axial area gradually widened toward the middle and expanded into a fascia reaching the margin; striæ divergent in the middle, convergent at the ends, 11 in 10 µ. L. 52 µ.
Pensauken, N. J., artesian well.
Pl. 29, Fig. 16.
PINNULARIA MICROSTAURON (EHR.) CL.
Valve convex, linear, tapering to sub-cuneate or sub-rostrate ends; axial area very narrow; central area a broad fascia; striæ divergent in the middle, convergent at the ends, 12 in 10 µ. L. 35 µ.
Pavonia, N. J., artesian well.
Pl. 29, Fig. 19.
This form does not exactly correspond to Cleve's diagnosis, as the ends are not broad. All species in the group Capitatæ are quite variable.