_Diagnosis with P. cornucopia._--The reddish-orange colour of the valves alone suffices. There is a very slight difference, in the larger proportional size of the upper latera, and in the outline of the basal margin of the carina. In the maxillæ there is, in _P. elegans_, a greater width between the two upper tufts of fine spines. In the cirri, the segments in the first pair, are more than half as many as those in the sixth pair; in the anterior ramus of the second pair, only 4/15ths of the segments are protuberant and brush-like, whereas in _P. cornucopia_ 5/12ths are in this condition. 3. POLLICIPES POLYMERUS. Pl. VII, fig. 2. POLLICIPES POLYMERUS.(!) _G.B. Sowerby._ Proc. Zool. Soc., 1833, p. 74. --MORTONI. (!) _Conrad._ Journal Acad. Nat. Sci. Philadelphia, vol. vii, p. 261, Pl. xx, fig. 12, 1837. _P. capitulo, valvarum duobus, tribus, aut pluribus sub-rostro verticillis instructo: valvis sub-fuscis: lateribus à supremo ad infimum gradatim quoad magnitudinem positis: carinæ margine basali (introrsùm spectanti) ad medium excavato: pedunculi squamarum verticillis densis, symmetricè dispositis._ Capitulum with two, three, or more whorls of valves under the rostrum: valves brownish: latera regularly graduated in size from the uppermost to the lowest: carina with the basal margin, (viewed internally,) hollowed out in the middle: scales of the peduncle symmetrically arranged in close whorls. Maxillæ with three tufts of fine bristles, separated by larger spines; caudal appendages uniarticulate; filamentary appendages attached to the prosoma. Upper California, St. Diego and Barbara, 32° to 35° N., according to Conrad; Mus. Cuming: Low Archipelago, Pacific Ocean; Mus. Coll. of Surgeons: Southern Pacific Ocean, collected during the Antarctic Expedition, Mus. Brit.