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Show 1906.] CRUSTACEA OF THE THIRD TANGANYIKA EXPEDITION. 199 It is extremely difficult to determine exactly the number of gills in species so small as those described below; and the following formula for C. cunningtoni is given with the reservation that some minute vestiges of gills may have been overlooked. The absence of the posterior pleurobranchia, however, as well as the absence of an epipod from the penultimate legs, are characters which it is comparatively easy to demonstrate and which seem to justify the establishment of the new genus. Branchial formula of Cardiella cunningtoni. Pleurobranchiae j Arthrobranchiae ; Podobranchiae mxp. 1 0 0 ep. mxp. 2'mxp. 3 0 0 ep. 0 r. ep. per. 1 per. 2 i 1 0 ep. 1 0 ep. per. 3 1 0 ep. per. 4 1 0 0 per. 5 0 0 0 In the case of C. cunningtoni, the large and peculiar first pair of chelae and the unarmed dactyli of the third and fourth pairs of legs are striking features. They are not shared by C. minuta, but owing to the small size of this species and the fact that only one adult specimen was found it has not been possible to make a complete examination of its characters, and it may yet prove to belong to a distinct genus. CARIDELLA CUNNINGTONI, n. sp. (Plate XIII. figs. 45-52.) Description.-Rostrum (Plate XIII. fig. 45) reaching nearry to end of second segment of antennular peduncle, less than half 3-5-1-8-12 length of carapace, slightly deflexed, teeth : 2_5 ". Antennular peduncle (Plate XIII. fig. 46) reaching to end of antennal scale, second and third segments longer than broad, external spine of first segment reaching to end of segment, distal spine reaching to middle of succeeding segment. Distal edge of antennal scale (Plate XIII. fig. 47) hardly projecting beyond external tooth. Third maxilliped not extending to end of antennular peduncle. First peraeopods (Plate XIII. fig. 48) very stout, reaching to about end of penultimate segment of third maxillipeds; merus produced as a blunt tooth above articulation of carpus; carpus less than twice as long as broad, distinctly excavated distally; chela more than one and a half times as long as carpus and much broader, less than two and a half times as long as broad; fingers a little shorter than the palm, gaping widely, a stout curved tooth at base of immovable finger fitting into a notch at base of dactylus, apical brushes scanty and short. Second peraeopods (Plate XIII. fig. 49) slender, extending beyond tip of third maxillipeds ; carpus about seven times as long as broad ; chela shorter than carpus, nearly four times as long as broad, fingers one and a half times as long |