ABSTRACT
Cirripedes are ordinarily bisexual, in which they differ from all crustaceans: when the sexes are separate, the males are minute, rudimentary in structure, and permanently epizoic on the females. To these latter facts of partial analogy in some of the suctorial entomostracans; but a far closer analogy in certain rotifers, which are considered by many naturalists as crustaceans. The male excretory organ is probosciformed and capable of the most varied movements; it is single and medial; it is seated at the extremity of the abdomen, and therefore near the normal position of the anus. Cirripedes are commonly bisexual or hermaphrodite, but in Ibla, Scalpellum, and Alcippe, members of the Lepadidae in the order Thoracica, and in Cryptophialus in the order Abdominalia, the sexes are separate. The males of Scalpellum vulgare, ornatum, and rutilum, resemble each other in all essential points, and differ wonderfully in appearance and structure from all ordinary cirripedes.
