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

322 COLLECTIONS FKOJl MELANESIA.have the articular ridges somewhat reflexed. Por its distributionsee Darwin's monograph (p. 279), by whom it is recorded fromMoreton Bay.3. Acasta sulcata, LamarcJc, var.A single specimen in the collection from Albany Island, 3-4 fms.,is very doubtfully referred to this species. It agrees generally inits external characters with Mr. Darvvin's description, and also inthe broader spur of the tergum of the operculum. In the remarkablereduction of the width of the parietes of the carino-lateral compartmentsit altogether resembles a specimen from Sydney in Mr.Cuming's collection (now in the British Museum) specially referredto by Mr. Darwin * ; but it differs very remarkably in the externalarmature of the parietes of the other compartments, which arearmed with strong, outwardly-projecting, bluntly-triangulate lobesor teeth, one such tooth being situate on each compartment, notvery far below the apex, except on the carina, where there are twoteeth ; thus there are five in all. The cup-shaped basis of the shellis pinkish ; the epidermis, which remains upon the basal half of thecompartments, bright yellow.Mr, Darwin (t.c. p. 311) mentions some remarkable variations inthe external armature of this species, but none which at all resemblethe specimen now described. In the very closely allied A. spongitesthe calcareous projections of the shell are often of considerablesize, yet not nearly so large as the teeth in the specimen fromAlbany Island, and much more numerous and irregularly distributed.In the specimen of A. sulcata from Sydney, with narrow-linearcarino-lateral compartments, the walls of the shell are externallysmooth.* Monograph of Cirripeclia, Ealauidte, p. 310 (1854).