42 MR. A. WHITE ON NEW CRUSTACEA. [JaU. 22, This species is most like the young of T. gangeticus ; but the dorsal spots are solid, not annular; and the head is olive, dotted with black. It has some affinity to Trionyx tuberculatus of Dr. Cantor from Chusan, which appears, from a drawing by Dr. Cantor in the Indian Museum at Fifehouse, to be distinct from any of the other Asiatic species that have occurred to me. That species has eight large and four small white-edged black spots, placed in pairs, on the dorsal disk, the throat witli a dark streak on the middle of eacli side, the chin yellow, black-dotted. The lateral sternal callosities are large, oblong, and the posterior one round. 4. Descriptions of Two Species of Crustacea belonging TO the Families Callianassid.e and SauiLLiD^E. By Adam White, Assistant Zool. Dep. Brit. Museum. (Plates VI. and VII.) The Callianassa here described is from the Camaroons River, W. Africa, whence it was brought by the captain of an African trader to J. Aspinall Turner, Esq., M.P., the well-known possessor of a very fine collection of African insects. Mr. Turner liberally presented it to the Museum, with the information, that this long-bodied Crusta-cean appears periodically in the river in prodigious numbers, which disappear in the course of ten days or a fortnight. The natives are very fond of them, as they are delicious eating ; and as soon as they make their appearance in the river, the men leave their usual pursuits to catch them. Genus Callianassa, Leach. Callianassa turnerana, n. s. (PI. VI.) C. processu rostrali brevifer trispinoso ; digito superiore obtuso, intus quadridentato ; abdominis segmentis tertio quarto quinto-queplagis duabus pellucidis, pilis densis brunneis postice obsitis. Long. unc. 6J. Hab. Africa occ. (Camaroons). Moveable finger of the large claw blunt at the end, the back gra-dually curved, the base with three or four small tubercles arranged longitudinally, and with indications of another row ; the inner edge has four teeth, the two largest near the base, united so as to form one large lobe with another tubercle inside. There is a considerable space left between the moveable finger and the fixed one ; the edge of the latter is toothless, but is hollowed on the inside and at the base, where it is covered with closely placed rounded tubercles ; the im-moveable finger is not much arched, and is pointed. The outside and greater part of the inside of the claw are very smooth, the lower edge being fringed with long and rather coarse hairs, which are ar-ranged in tufts, as they are also, in a double row, on the upper edge of the moveable finger. There are, besides, four rows of distant tufts
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