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A Monograph on the Sub-class Cirripedia (Volume 2 of 2) / The Balanidæ, (or Sessile Cirripedes); the Verrucidæ, etc., etc. cover

A Monograph on the Sub-class Cirripedia (Volume 2 of 2) / The Balanidæ, (or Sessile Cirripedes); the Verrucidæ, etc., etc.

Chapter 277: PLATE 24. Genera—CRYPTOPHIALUS AND PROTEOLEPAS.
By Charles Darwin
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This work presents a detailed monograph on the sub-class Cirripedia, focusing on various species of barnacles, including the Balanidæ and Verrucidæ. It includes comprehensive descriptions, classifications, and illustrations of these organisms, contributing to the understanding of their biology and taxonomy. The author examines their anatomical features, reproductive habits, and ecological roles, providing insights into their adaptation and evolution. The text serves as a significant resource for naturalists and biologists interested in crustacean studies, reflecting the author's meticulous research and dedication to the field.

PLATE 24.
Genera—CRYPTOPHIALUS AND PROTEOLEPAS.

CRYPTOPHIALUS MINUTUS.

  • Fig. 10, Lower enlarged end of œsophagus, where entering the stomach, viewed from one of the sides bearing the discs of teeth; a, upper cut off end of œsophagus; b, the lower end and natural opening; c, thickened rim, having a somewhat beaded structure.
  • 11, The same; diagram giving a transverse section of the above in the line of the discs of teeth; c c c c, four thickened beaded edges; e e, two other but narrower and less prominent beaded edges; d d, discs of teeth; f, rows of fine bristles; the almost double row of bristles on each side under (d) is not of course seen in this section.
  • 12, Lower end of œsophagus viewed from a position at right angles to that in fig. 10; or from the side e, of the diagram, fig. 11; the two discs of teeth are consequently shown in profile; a, upper cut off end of œsophagus; b, lower natural end; c, c, thickened edges; e, narrower thickened edge, projecting towards the beholder; d, disc of teeth seen in profile.
  • 13, Portion of one of the cirri; a, lower segment of pedicel; b, upper segment, supporting the two rami.

  • 14, Segments of one of the rami much enlarged; a, thickened shield-like portion of membrane.
  • 15, Ovum, (thirty-five times the natural size.)
  • 16, Egg-like larva in the first stage, on same scale.
  • 17,””in the second stage, on same scale.
  • 18, Larva in the last or pupal stage, on four times the scale of fig. 15-17; a, antennæ; b, apodeme and eyes; c, abdominal bristles. A male would have been developed from this pupa.
  • 19, Male on same scale as the pupa, fig. 18; a, three terminal segments of the antennæ of the pupa; d, orifice of the sack.

PROTEOLEPAS BIVINCTA.

  • Fig. 1, Antenna of the pupa (three terminal segments of), with a portion
    of one of the two threads, enclosing the cement-ducts, by which the body of the Proteolepas is attached; the upper portion of the thread, and the adjoining part of the body, are represented in section.
  • a, part of the great mass of cellular matter within the ovarian sack, in process of development into ova, and changing its character as soon as it enters the tube or cement-duct.
  • b, membrane forming the ovarian sack and the cement-ducts, the latter enclosed within the threads of attachment.
  • c, corium lining the outer membrane of the body, and the upper part of the threads.
  • d, outer membrane of body.
  • e,””becoming suddenly thicker where forming the outer membrane of the thread.
  • e′, outer membrane of the thread in the lower part, here not shown in section.
  • f, main or second segment of the pupal antenna, the basal segment having, as in all cases, been moulted, with the carapace of the pupa.
  • g, disc-segment, apparently with a small orifice for the issuing of the cement.
  • h, terminal segment with the shorter spines broken off.
  • 2, Compounded mandibular organ, sketched by the camera; a, supposed mandible; b, perhaps portion of the mandible; c, maxilla; d, ligamentous fibres giving attachment to muscles.
  • 3, Mouth seen from the ventral side, sketched by the camera; r, articulation separating the mouth from the body; c, compounded mandibular organ; d, palpus, united to the opposite palpus and to the crest of the labrum; the latter forming the back of the hollow in which the compound mandibles work.
  • 4, Diagram of the mouth of an ordinary cirripede, seen from above; a, outer maxilla; b, maxilla; c, mandible; d, labrum.

  • 5, Diagram, illustrating the supposed changes in position of the gnathites in Proteolepas, causing them to stand back to back; a, outer maxilla; b, maxilla; c, mandibles; d, labrum.