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Show '46 MR. W. F. LANCHESTER ON CRUSTACEANS [June 19, I note the following sexual differences in this species:- Males. The hind margin of the abdomen as seen from below ('. e. hind margin of 3rd segment) is medianly emarginate, and curved forward at the sides. The first and second sternal segments are crossed by transverse rows of granules, which are prominent in the larger examples. Females. The bind margin of the abdomen not, or very faintly, emarginate, and almost transverse ; first and second sternal segments smooth. Dim. d 15-5x9-5. d 15 x 9. d 15-5x9. d 10-5x6. d 12x19. $ 4-75x8. XXXVIII. Genus ACHELOUS de Haan. 62. ACHELOUS WHITEI A. M.-Edw. Achelous whitei, A. M.-Edw. Arch. Mus. t. x. p. 343, pi. xxxi. f. 6 (1861); Walker, Journ. Linn. Soc, Zool. vol. xx. p. 110 (1887) ; Henderson, Trans. Linn. Soc, Zool. vol. v. p. 371 (1893). Hab. Singapore ; up to 12 fms. An adult male and adult female ; a spurious male, with the whole of the under surface covered with parasitic organisms, and a spurious female, less densely beset with the same parasite ( = a Sacculma). In the adult female the last (epibranchial) spine is but little bigger than those in front, and the breadth of tbe carapace is relatively less than in the male. Dim. d 18x11-5. $ 16x12. 63. ACHELOUS RUBRO-MARGINATUS, sp. nov. (Plate XLVI. fig. 8.) Hab. Singapore ; taken from off a floating piece of wood. A single specimen, a female. Carapace only moderately broad, and somewhat convex, covered with numerous, evenly disposed, and granulated prominences, between which is an exceedingly dense, short pubescence; this extends on to the prominences, but not so as to conceal the granules on them, which are quite smooth and rounded. Frontal lobes six : two median, short and conical, separated by a wide fissure from the submedian, which are broader and directed more obliquely outwards than the median, but do not project farther forwards ; a deeper, wider, fissure separates these from the laterals, which are broad and less prominent, and form the internal orbital angle. All these lobes are granulated. Superior orbital margin granulated, with two fissures ; tooth of external angle broad and salient; tooth next behind this about half the size, and the six antero-lateral teeth following equal, and still smaller than the second, all directed forwards; last tooth strong, a very little larger than the external tooth of the orbit, and with its point curved forwards. Lower orbital border granulous, with a deep fissure in its external half ; internal angle of this lower border forming a strong and prominent tooth. Basal joint of antennas broad, and reaching the infero-lateral process of the front, next joint moderately dilated; flagellum smooth and not very long. Ischium |
