Capitulum

Definition and stakes

Portrait of Charles Darwin Charles Darwin,  A Monograph on the Sub-class Cirripedia…

“ There is here no distinction between a peduncle and capitulum, that is between the lower or anterior, and the upper or posterior end of the animal, as seen externally. The small orifice is toothed and hairy: it is coloured purple, as is likewise the projecting labrum; the rest of the animal being tinted only by the muscles and internal parts seen through the outer integuments. ”
Source: Gutenberg

Portrait of Charles Darwin Charles Darwin,  A Monograph on the Sub-class Cirripedia…

“ Description.—The Capitulum is much compressed, and generally produced upwards; it is formed of from twelve to fifteen valves, which are rather thin, and with the exception of S. ornatum, almost entirely covered by membrane, bearing spines: the valves are seldom locked very closely together. A sub-rostrum exists only in S. villosum, which species leads on to Pollicipes; in S. vulgare the rostrum is rudimentary and hidden. ”
Source: Gutenberg

Portrait of Charles Darwin Charles Darwin,  A Monograph on the Sub-class Cirripedia…

“ In Scalpellum, I ascertained that the new membrane, connecting together the newly-formed calcified rims under the valves of the capitulum, was formed as a fold, with the articulated spines which it bears, all adpressed in certain definite directions. This fold of new membrane, when the old membrane splits and yields, of course expands, and thus the size of the capitulum is increased. In the peduncle, lines of splitting can seldom be perceived, except, indeed, in the sub-globular, embedded, downward-growing peduncle of Anelasma, as described under that genus. ”
Source: Gutenberg

Get perspective with Kwize: daily news enlightened by great literature