Complemental male, attached externally between the scuta, below the adductor muscle; pedunculated; capitulum formed of six valves, with the carina not descending much below the basal angles of the terga: mouth and cirri prehensile.

Eastern Seas[60] (?) attached to shells and rocks. Mus. Brit.; College of Surgeons; Cuming.

[60] No habitat is attached to any of these specimens; but Mr. Sowerby informs me that he has seen specimens attached to the Modiola albicostata of Lamarck, which shell is said by the latter author to be found in the seas of India, Timor, and New Holland.

HERMAPHRODITE.

Capitulum with fourteen valves, consisting of a pair of scuta and of terga, a carina, (which five valves are much larger than the others,) a rostrum, sub-rostrum, sub-carina, and three pair of small latera. All the valves are covered by membrane, as are the calcareous scales on the peduncle; and this membrane everywhere is densely clothed with spines. The upper valves are not very thick; they stand rather close together. The eight valves of the lower whorl are more solid, and are placed far apart; they are small, tending to become rudimentary. None of the valves are added to at their upper ends, in which respect this species differs remarkably from the others of the genus, and approaches in character to Pollicipes.

Scuta, with a deep hollow for the adductor muscle, triangular, with the basal margin elongated, and protuberant.

Terga, large, flat, triangular, basal point blunt, with the carinal margin slightly hollowed out, and the scutal margin protuberant. Apex solid.

Carina, rather longer than the terga, straight, gradually widening from the upper to the basal end, deeply concave. In young specimens the upper part is slightly bowed inwards. Apex solid.

Sub-carina, with the inner surface crescent-shaped; the umbo points transversely outwards; in width it exceeds the largest of the latera.

Rostrum, triangular, internally ([fig. 8 a]) concave; basal margin slightly hollowed out, and deeply notched; rather less in width than the carina; short, with the umbo pointing upwards and outwards. In young specimens the apex curves a little inwards.