1903. | ON A NEW FRESHWATER CRAB FROM UPPER GUINEA, 41 
Puate VIII. 
Fig. 11. Transverse section of brain behind origin of cesophageal commissures, to 
show giant ganglion-cells. 290. R.M., retractors. .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 §.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 circumcesophageal commissures (X 53 and reduced). p. 34. 
A. Circumcesophageal 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. 
D. Fused retractor muscles. 
i}. Blood-sinus. 
Fig. 17. Diagram of a nephridium. _ A, excretory canal. B, calomic 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 scen forming 
feathery columns. E, vesicles. p. 36. 
5. On Potamon (Potamonautes) latidactylum, a new Fresh- 
water Crab from Upper Guinea. By Dr. J.G. pu May, 
of Ierseke, Holland." 
[Received November 15, 1902.] 
(Plate 1X2) 
In the year 1881, Potamon africanum A. M.-E. was known only 
by the short diagnosis and the figures in the ‘ Nouvelles Archives 
du Muséum,’* 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 were referred by me erroneously to this 
species *. 
Some time since, three adult specimens of a Potamon were sent 
me for examination by Prof. Jeffrey Bell ; they had been collected 
in the River Prah, 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. afri- 
canum, a middle-sized female from “ Ogoué” (evidently the 
River Ogowé, 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. Jerrrey Bert, F.Z.8. 
For explanation of the Plate, see p. 47. 
3 Vol. v. p. 186, pl. xi. fig. 2 (1869). 
Telphusa africana de Man, Notes Leyd. Mus. iii. p. 121 (1881). 
bo 
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