Report on the zoological collections made in the Indo-Pacific Ocean ...

CRUSTACEA. 291or lobe on its inner margin, which fits into a cavity between twosmaller teeth on the inner margin of the lower finger. These charactersare, however, less marked in specimens in which the secondlegs are less developed, and there are one or two examples in whichthe chelae scarcely difterin form and proportions from Dana's figure ;hence I have not ventured to regard the species as distinct.A specimen, dried and very imperfect, which probably belongs tothis species, is in the British-Museum collection from Keppel Island,Port Curtis, obtained within the shell of a live Pinna (j. MacgiUivrmj,H.M.S. 'Rattlesnake'), others from the collection of H.M.S.'Herald,' from the interior of Trklacna (without indication oflocality), and others from Matuka and Ngau (IT. M.S. 'Herald').In all the specimens from the ' Herald ' collection the second pairof chelipedes are less developed, as in Dana's figure of this species,which was based on a specimen from Tutuila, in the Samoan orNavigator group (Crust. U.S. Expl. Exp. xiii. p. 571, pi. xxxvii.fig. 1, 1852).It appears very doubtful whether the P. maculata, Stimpson*,from Tridacno' obtained at Bonin, can be regarded as distinct fromP. tridacncp, from which it is only distinguished by Stimpson byits elongated form and slenderer rostrum ; the rostrum is, however,described as reaching only to the penultimate joint of theantennulary peduncles (and hence shorter than is usiial in P. tridacna')and truncated at apex.The genus ConcJiod.yfes, established for this species by Dr. Peters,can, I think, scarcely be regarded as generically distinct fromPontonia ; but the name may perhaps be conveniently retained as asubgeneric designation for P. trklacna' and the allied species. Dr.Hilgendorf, who had the opportunity of examining Dr. Peters'stype, distinguishes it from Pontonia merely by the shorter antennalflagellum t but the flagellum in P. macrophtJialma (which Dr. Peters;himself supposes to belong to Conchodytes) is represented as beingmuch longer. (See M.-Edwards, Atlas in Cuvier's Regno ' Animal,'Crustaces, pi. lii. fig. 3.)12. Harpilius inermis. (Plate XXXII. fig. B.)Body not compressed, smooth, and dorsally rounded, and withoutspines either on the carapace or postabdomen. Rostrum spiniform,rounded and smooth above, longer than the eye-peduncles, ratherbroad at base, appearing acute at apex in a dorsal view, withoutspinules or teeth on its upper or lower margins ; it is laterallysomewhat compressed, and in a lateral view its apex is rounded.The terminal postabdominal segment is rounded above, but narrowsconsiderably towards its distal end, which boars several set;e ; thelateral margins are unarmed. The eye-peduncles project laterallyand are of moderate size ;the antennulary peduncles project slightly* Proc. Acad. Nat. Sci. Philad. p. .38 (1800).t Sitzungsb. der Akad. Wiseensch. Berlin, p. 835 (1878).V2