Fig. [64].—Alcippe lampas. A, ♀, × about 10, seen from the right side, with part of the right half of the animal removed; B, dwarf male, × about 30. A.M, adductor muscle; An, antenna; C, 1st pair of cirri; Cr, posterior thoracic appendages; E, eye; G, testis; M.C, mantle-cavity; O, ovary; P, penis; T, penultimate thoracic segment; V. vesicula seminalis. (After Darwin.)
Darwin discovered and described Cryptophialus minutus, and placed it in a sub-order Abdominalia, believing that it was distinguished from all the foregoing Cirripedes by the presence of a well-developed abdomen. Since the discovery of other allied genera, it has been decided that the abdomen is equally reduced in these forms, and that the terminal appendages do not belong to this region, but to the thorax.
The sexes are separate. The body of the female (Fig. [64], A) is enclosed in a chitinous mantle, armed with teeth by which the excavation is effected, and is attached to the cavity in the host by means of a horny disc. Upon this disc the dwarf males (B) are found.
Alcippe lampas inhabits holes on the inner surface of dead Fusus and Buccinum shells; Cryptophialus minutus the shells of Concholepas peruviana; C. striatus [[68]] the plates of Chiton; Kochlorine hamata the shells of Haliotis; and Lithoglyptes varians shells and corals from the Indian Ocean.
Sub-Order 4. Ascothoracica.
These are small hermaphrodite animals completely enveloped in a soft mantle, which live attached to and partly buried in various organisms, such as the branching Black Corals (Gerardia). They retain the thoracic appendages in a modified state, and the body is segmented into a number of somites, the last of which probably represents an abdomen.
Laura gerardiae, described by Lacaze Duthiers,[[69]] is parasitic on the stem of the “Black Coral,” Gerardia (vol. i. p. 406); it has the shape of a broad bean, the body being entirely enclosed in a soft mantle, with the orifice in the position corresponding to the hilum of a bean. The body lying in the mantle is composed of eleven segments, and is curved into an S-shape. Its internal anatomy is entirely on the plan of an ordinary Cirripede.
Petrarca bathyactidis, G. H. Fowler,[[70]] was found in the mesenteric chambers of the coral Bathyactis, dredged by the Challenger from 4000 metres. The body is nearly spherical, and the mantle-opening forms a long slit on the ventral surface. The mantle is soft, but is furnished on the ventral surface with short spines.
The antennae, which form the organs of fixation, remain very much in the state characteristic of the Cypris larvae of other Cirripedes, being furnished with two terminal hooks by which attachment is effected. The thoracic appendages, of which there are the normal number six, are reduced flabellate structures, and the abdomen forms an indefinitely segmented lobe of considerable size.