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Show 538 DR. J. G. DE MAN ON CRUSTACEANS [Dec. 12, The female from Christmas Island is of a somewhat larger size than Heller's type specimen ; the measurements are the same, except that the greatest width of the carapace of the female from Christmas Island is a little larger in proportion both to the length of the carapace and to the distance between the external orbital angles. The exognath of the external maxil-lipedes, though still less broad than the iscliium-joint, appears broader in proportion to this joint than in Heller's younger type specimen, and the chelfe are comparatively larger. The tips of both fingers carry some stiffish hairs on their outer surface close to the horny border ; these hairs are more numerous on the tip of the fixed finger. In the Vienna type specimen these hairs were, no doubt, worn off. The dactylus carries 6 or 7, acute, conical teeth, and the fixed finger 4 or 5, which are a little larger. These slight differences are caused by the larger size of this specimen, which, for the rest, fully agrees with Heller's type. The male is larger than the female and more than once and a half as large as Heller's type specimen ; regarding the proportion of the measurements of the carapace, the male agrees with the female from Christmas Island. The cephalothorax also fully agrees in its other characters with my description of 1895, except as regards the outer footjaws. I suggested in that paper that, in the male, the exognath should be as broad as or perhaps even a little broader than the ischium-joint; this supposition is now confirmed by the male from Christmas Island. In this male, indeed, the exognath (PI. XVII. fig. 3) appears a little broader than the ischium, the proportion between them being as 1 1 : 1 0 ; the exognath is distinctly convex longitudinally and also a little transversely. The merus-joint fully agrees with that of the type specimen, its anterolateral angle being rounded, whereas the external margin, so far as it is contiguous to the exognath, appears very slightly concave ; the outer half appears, under a lens, finely granulate. The exognath is somewhat punctate, except on the inner border and posteriorly, as is also the endognath, except in the middle, and short stiff seta; are inserted on the puncta. The abdomen (fig. 4) resembles that of Ptych. polleni de M. from Madagascar (de Man, I. c. Taf. 28. fig. 20 b), as is proved by the figure and the measurements. Sternum and abdomen are punctate; the 3rd, 4th, and 5th segments of the abdomen, counting from the base, carry, moreover, each a larger pit on their antero-lateral angle and another on the anterior half at either side of the middle line. The chelipedes are equal (fig. 1). The punctate, anterior surface of the ischium carries one or two short, stiff setse. The upper border of the merus is hairy on its proximal half, the obtuse anterior border is granular and a little pubescent proximally. The upper surface of the carpus is closely, but finely punctate, the rest smooth, but it appears finely granular under a lens in the female; the internal angle is obtuse, though not rounded. The chelae (fig. 5) resemble closely those of Ptych. barbatus, not only as regards their general shape but also because |