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Show 706 MR. W. T. CALMAN ON MACRCROUS [May 16, far as the end of the first joint of the peduncle of the antennules. There is on the outer surface of the coxal joint a conical curved papilla similar to, but smaller than, the papilla to which the epipod of this appendage, here absent, is attached in G. wyckii. The exopod exceeds in length the joint from which it springs. The terminal joint is shorter than the penultimate joint, and presents a remarkable structure (fig. 9a). About the middle of its length there is a deep excavation of the inner side, a little beyond which distally stands a stout curved spine ; a double row of strong toothed spines smaller than the preceding and gradually diminishing in size, fringe the distal margin of the notch ; the oblique posterior or proximal margin is fringed with feathered or pectinate setae. Beyond the notch, the inner margin of the joint bears a series of 6-7 short spines leading up to the pointed apex of the limb. I am not aware that an arrangement similar to this is found in other Atyidce. In G. wyckii there is only a very slight concavity of the inner margin of the joint, clothed with numerous spines and setae. The first pair of peraeopods (Pl. X L . figs. 10,10a) do not reach to the terminal joint of the third maxillipeds. The ischium and merus are short and subequal. The carpus is conical in shape, rather more than one-half as broad as long, about equal in length to the merus, and slightly longer than the palmar portion of the hand ; it is slightly excavated distally on the inner side (fig. 10 a). The hand is long aud narrow, the breadth being about one-third of the length. The fingers are slender, longer than the palm, spoon-shaped, but acutely pointed as seen from the side, instead of truncate as in G. wyckii. The opposed margins bear series of small stout spinules increasing in size towards the tip, but there is no strong terminal hook as in 0. wyckii. The brushes of setae borne by the fingers are very scanty compared with those of C. wyckii. The second peraeopods (Pl. X L . fig. 11) reach forward as far as the tip of the third maxillipeds. The ischium is a little lono-er than the merus and about equal to the carpus. The latter is cylindrical and only slightly wider distally. The hand is longer than the carpus by one-third the length of the latter, and its breadth is less than one-quarter of its length. The fingers are very long and slender, about twice as long as the palm, sharply pointed, and with scanty terminal brushes. The third pair of peraeopods extend beyond the third maxillipeds when turned forward, and the last pair fall short of them. The dactyl us is one-third to two-fifths the length of the propodus. The dactylus of the last pair (Pl. X L . fig. 13a) is similar to the preceding two pairs, having only a slightly larger number of spines on its inner margin, the numbers being from 11 to 15 in the case of the third and fourth peraeopods, and from 16 to 19 in the last pair. In Caridina the dactylus of the last peraeopods is longer aud bears a much more numerous series of spines than do those of the preceding two pairs. In a specimen of G. wyckii, for example, the dactyli of the third and fourth pairs bore 7 and 8 spines' |