ABSTRACT
Scalpellum villosum, a recent species, has stronger claims than any other species to be generically separated; and its habits, in not being attached to horny corallines, are also different. Scalpellum Peronii, villosum, and rostratum, in having a subcarina in the rostrum being pretty well developed and in the complemental male being pedunculated, and furnished with a functional mouth and prehensile cirri. The peduncle, which is generally rather short, and, with the exception of Scalpellum Peronii, is covered with calcified scales. These scales are generally small, and placed symmetrically in close whorls, in an imbricated order. In the males, however, of Scalpellum rostratum, Scalpellum Peronii, and Scalpellum villosum, compared one with another, but not with the males of other species, the parts of the mouth and apparently the cirri, resemble each other more closely, than do the same organs in the hermaphrodites. All the species, except Scalpellum villosum, are attached to horny corallines: the singular means of attachment in Scalpellum vulgar.
