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Show Plate V I I I . Fig. 11. Transverse section of brain behind origin of oesophageal commissures, to show giant ganglion-cells. X 290. R.M., retractors. B.S., blood-sinus. G.C., giant cells, p. 33. Figs. 12, 13, 14, 15. Four transverse sections through the brain and base of the tentacular crown, to show the epineural canal and formation of the eye-spots. X 53. B.S., blood-sinus. V.C., nerve-cord. R.M., retractor muscles. S.E., sensory epithelium of the dorsal, and S.V., that of the ventral wall of the epineural canal. T, tentacles. S.P., eye-spots. E, epithelium of anterior cerebral surface, p. 34. Fig. 16. Transverse section through brain and bases of the tentacles, showing the origin of the circumoesophageal commissures (X 53 and reduced), p. 34. A. Circumoesophageal nerves. B. Nerves to the epineural canal and dorsal pair of tentacles. C. Two nerve-strands, in cross section, which seem to be connected with the sense-organs. I). Fused retractor muscles. E. Blood-sinus. Fig. 17. Diagram of a nephridium. A, excretory canal. B, coelomic pore. C, vesicle. D, tubular part. E, body-wall. p. 36. Fig. 18. To show histology of tubular portion. X 290. A, peritoneal cells. B, muscular wall. C, secreting cells which at D are seen forming feathery columns. E, vesicles, p. 36. 1903.] ON A NEW FRESHWATER CRAB FROM UITER GUINEA. 41 5. On Potamon (Potamonautes) latidcictylum, a new Freshwater Crab from Upper Guinea. By Dr. J. G. du Man, of Ierseke, Holland.1 [Received November 15, 1902.] (Plate IX .2) In the year 1881, Potamon africanum A . M.-E. was known only by the short diagnosis and the figures in the 4 Nouvelles Archives du Museum,' 3 made from a quite young individual from the Gaboon. The anterior legs had neither been described nor figured, and it is therefore not surprising that some older specimens of a Potamon from Liberia wTere referred by me erroneously to this species 4. Some time since, three adult specimens of a Potamon were sent me for examination by Prof. Jeflrey Bell; they had been collected in the Biver Prali, in the south of Ashanti, West Africa. These Crabs not only proved to belong to the same species as that described by me in 1881, when compared with a female of medium size and a very young male from Liberia in the Leyden Museum, but they proved also to be new, as a typical specimen of P. africanum, a middle-sized female from " Ogoue " (evidently the Biver Ogowe, just below the Equator), was kindly sent me by Prof. Bouvier, and as a more complete description of P. africanum was published in 1887, in which, however, the legs have not been 1 Communicated by F. J e e f k e y B e l l , F.Z.S. 2 For explanation of the Plate, see p. 47. 3 Vol. v. p. 186, pi. xi. fig. 2 (1869). 4 Telphusa africana de Man, Notes Leyd. Mus. iii. p. 121 (1881). |