_Mouth._--Labrum bullate, with teeth on the crest. _Palpi_ blunt, spinose. _Mandibles_, with three teeth; inferior point rather strongly pectinated. _Maxillæ_, with a considerable notch under the upper pair of large spines; inferior part of the edge not prominent. _Outer Maxillæ_, with the spines on the inner edge arranged into two groups. Olfactory orifices tubular and prominent, with some long bristles near their bases. In the mandibles having only three teeth, in the maxillæ being notched and in the lower part not being prominent, and, lastly, in the bristles on the inner face of the outer maxillæ being arranged in two groups, these several organs differ from those in the hermaphrodite. _Cirri._--First pair short, with only three or four segments in each ramus: second cirrus, with the basal segments not very thickly clothed with spines: sixth cirrus with seven segments, not protuberant in front, each bearing four pairs of spines, without intermediate tufts. _Caudal appendages_, none. This is an interesting fact, considering that these organs are likewise absent in the hermaphrodite _S. villosum_,--an absence highly remarkable, and confined to the genus Conchoderma and the one species of Anelasma. _Penis_ thick, not tapering, rather exceeding in length the pedicel of the sixth cirrus, square at the end, and furnished with some spines. In one specimen, I believe I distinguished the vesiculæ seminales: if so, they contained only pulpy matter, and not spermatozoa. There were no ovarian tubes within the peduncle, which was lined by the usual muscles; I traced the two delicate cement-ducts, running from within the antennæ close up to the animal’s body. Hence in this case, as in that of _S. Peronii_, I dare positively affirm that ovarian tubes do not occur; for it is out of the question that I could have traced the cement-ducts, and, at the same time, overlooked the far larger and more conspicuous ovarian tubes, into which, moreover, the ducts, had they existed, would have run. Consequently, these parasites are not females; but judging from the probosciformed penis, and from the presence, as I believe, of vesiculæ seminales, they are males.