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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 273: PLATE 20. Genera—PACHYLASMA, OCTOMERIS, AND CATOPHRAGMUS.
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 20.
Genera—PACHYLASMA, OCTOMERIS, AND CATOPHRAGMUS.

  • Fig. 1 a, Pachylasma aurantiacum, shell, lateral view; A, rostrum, separated only by the finest suture from B, the rostro-lateral compartment, which latter has a mere rim-like radius on the side facing the lateral (C) compartment. The latter (C) has a great ala, and is separated from the (D) carino-lateral compartment, by the finest suture; D has a rim-like radius; E, carina, with very large alæ (a).
  • 1 b, Pachylasma aurantiacum, inside view of about half the shell, showing the compound rostrum, consisting of the true rostrum (A) and the two rostro-lateral (B, B) compartments; of the latter, that to the left has a shoulder, receiving the ala of the lateral compartment which has been removed; the ala of the lateral compartment extends, in the upper part, over the whole width of the rostro-lateral compartment, as may be seen on the right-hand, B; C, lateral compartment; D, carino-lateral compartment, with a shoulder (b) to receive the ala of the carina, which has been removed.
  • 1 c, 1 d, Pachylasma aurantiacum, scutum and tergum, external views of.
  • 2 a, Octomeris angulosa, shell seen from above; 2 b, scutum and tergum, internal views of.
  • 3 a, Octomeris brunnea, shell seen from above; 3 b, scutum and tergum, external views of.
  • 4 a, Catophragmus polymerus, shell seen from above.
  • 4 b,””external view of one of the scales or valves, from the second whorl, counting from the inside.

  • 4 c,””outline of the basal edges of all the valves of a shell; A, rostrum; B, rostro-lateral; C, lateral; D, carino-lateral compartments; E, carina.
  • 4 d,””external view of a portion of the shell of a much corroded and worn down specimen, serving almost as a transverse section; C, lateral compartment, D, carino-lateral compartment.
  • 4 e,””scutum and tergum, internal views of.