_Cirri._--The segments of the three posterior pairs bear four pairs of spines, with the usual intermediate fine spines; dorsal spines thin and thick mingled together. _First cirrus_, short, with the anterior ramus rather the thickest and shortest; all the segments thickly paved with bristles, except the two terminal segments, of which the ultimate one bears some serrated spines of most unusual length, namely, equalling within one segment the entire length of the ramus. I presume that these spines serve as feelers. _Second cirrus_; anterior ramus much thicker and considerably shorter than the posterior ramus; six basal segments paved with bristles, the two terminal segments having the usual structure; posterior ramus with all its nine segments on the usual structure. _Third cirrus_, longer, to a remarkable degree, than the second cirrus, with its anterior ramus having the four basal segments paved, and the seven terminal ones on the usual structure; posterior ramus with twelve segments, of which none are paved. The pedicels of the second and third cirri thickly and irregularly clothed with spines. The upper segments of the pedicels of all the cirri are unusually long. _Caudal Appendages_, longer than the pedicels of the sixth cirrus, by barely one third of their own length. Segments much elongated, seven in number; I may add for comparison that each ramus of the sixth cirrus contained, in this specimen, sixteen or seventeen segments. _General Remarks._--It is difficult to give obvious characters, (excepting the smallness of the rostrum compared with the scales on the peduncle,) by which this species can be externally discriminated from _L. dorsalis_, _L. Nicobarica_, and _L. Rhodiopus_; yet almost all the valves differ slightly in shape. In this species alone, (the peduncle of _L. Rhodiopus_ is not known,) the lower, microscopically minute, bead-like scales of the peduncle are crenated, though obscurely, all round. In the animal’s body, the diagnostic characters are strongly marked;--the long spines on the terminal segment of the first cirrus,--none of the segments in the posterior rami of the second and third cirri being thickened and paved with bristles,--the pectinations being equal in number between the main teeth of the mandibles,--are all characters exclusively confined to this species. 3. LITHOTRYA NICOBARICA. Pl. VIII, fig. 2. L. NICOBARICA. _Reinhardt_, Naturhist; Selskabet, Copenhagen. No. I. 1850. Tab. I, fig. 1-3.[68] [68] I am not at all sure that the proper title of the periodical in which this species has been described, is here given. I am greatly indebted to Prof. Steenstrup for sending me a separate copy of the paper in question, written in Danish. I believe I am right in identifying the specimen here described, from Timor, with the species from the Nicobar Islands, named by Reinhardt, _L. Nicobarica_.