_Affinities._--This genus differs from all, except Anelasma, in the manner in which the striæ-less muscles of the peduncle run up and surround the capitulum, and likewise in the reticulated character of the biliary envelope of the stomach. To Conchoderma, especially to _C. aurita_, there is manifest affinity in the form of the horny scuta: there is also some affinity to this same genus in the presence of filamentary appendages though here little developed, and in the circular form of the disc of the larval antennæ, and, lastly, in the ovarian tubes in _A. cornuta_ surrounding the capitulum. There is quite as close, if not closer affinity to Ibla, in the following peculiarities,--in the curved oesophagus,--in the general character of the cirri and trophi, with the olfactory orifices in one species in some degree prominent,--in the multi-articulated caudal appendages,--and in the plainly-articulated penis, with its elongated unarticulated support, though both these characters are exaggerated in Ibla. Lastly, the scuta in Ibla, though not at all resembling in shape those of _A. cornuta_, are formed without calcareous matter; and again, in Ibla, the muscles of the peduncle run up to the bases of the valves, and so almost surround the space in which the animal’s body is lodged. The four species of Alepas appear to form two little groups; viz. _A. parasita_ and _A. minuta_ on the one hand, and _A. cornuta_ and _A. tubulosa_ on the other. 1. ALEPAS MINUTA. Tab. III, fig. 5. ALEPAS MINUTA. _Philippi._ Enumeratio Mollusc. Siciliæ, 1836, Tab. xii, fig. 23. ---- ---- _A. Costa._ Esercitazione Accadem., vol. ii, part I, Naples, 1840, Pl. iii, fig. 5 (secundum Guerin in Revue Zoolog., 1841, p. 250.) ---- ---- _Chenu._ Illust. Conch., Pl. iii, figs. 8-10. _A. aperturâ non prominente, capituli longitudinis vix tertiam partem æquante: scutis corneis, pæne absconditis: longitudine totâ ad quartam unciæ partem._ Orifice not protuberant, one third of the length of the capitulum: scuta horny, almost hidden. Total length quarter of an inch. Outer maxillæ, with the spines in front continuous; posterior cirri, with several long spines arranged in a transverse row on each segment; caudal appendages longer than the pedicels of the sixth cirrus. Sicily; attached to a Cidaris:[43] island of Capri (_A. Costa_). [43] I am greatly indebted to Professor J. Müller, of Berlin, for kindly lending me specimens. Capitulum oval, blending insensibly into the peduncle; moderately flattened; composed of thin structureless membrane, with the exception of two horny, almost quite hidden scuta. Orifice situated near the summit, and in a line, which is oblique to the longitudinal axis of the peduncle; much wrinkled; barely one third of the length of the whole capitulum.