﻿D. 0. Leng — West Tropical Africa. 27 



The anterior portion of the body is curved, and in this region is 

 situated the eye, which is large, black, oblong, very prominent, and 

 placed much lower than in Cypris. The upper antennte, inserted 

 immediately below the eye, are long, setigerous, and composed of 

 five joints gradually diminishing in size. Each of these joints bears 

 on its upper part a tolerably long bristle, the fifth, however, is fur- 

 nished with two. The lower antennas consist of six joints, of which 

 the second, third, and fourth carry each a single bristle, whilst the 

 sixth has a tuft of four. 



Like all true Cypridce, it possesses two pairs of feet. The first 

 pair slender, composed of four joints and terminating in two curved 

 claws ; the second stouter, and, like the first pair, made up of five 

 joints, the last terminating in two long curved claws ; but it is also 

 furnished with two well-developed bristles, which spring from the 

 summit of the first joint. 



The jaws are not so distinctly visible in this fossil genus as the 

 previously described organs ; but M. Brongniart has been able to 

 distinguish in one individual a large mandible which is divided at 

 its extremity into several teeth, each provided with some very fine, 

 short hairs. Another individual exhibits a palpus of two joints, with 

 a pencil of fourteen medium-sized bristles attached to the terminal one. 



The post-abdominal ramus is short, stout, and broad at its ex- 

 tremity ; in some specimens (probably the females) it bears seven 

 jointed bristles of uniform length, but in others (the males?) it is not 

 so large, and provided with only four short bristles, one of which is 

 longer than the rest. At the posterior portion of the body of the 

 former appear two large black oval bodies, united at their bases, 

 which may be the ovaries. 



The author carefully notes the difl"erences existing between the 

 structure of the organs as exhibited in Palceocypris and that of the 

 corresponding organs in the recent genera of Cypris, Cypridopsis, 

 Notodromas, and Candona, at the same time pointing out that the 

 general similarity between them, as far as their oi'ganization is con- 

 cerned, is the more interesting when the immense interval of time 

 by which their periods of existence are separated is taken into con- 

 sideration. B.B.W. 



III. — Geological Notes on some parts of West Tropical Africa. 

 By D. 0. Leng. From the Eep. Imp. Geol. Instit. Vienna, June 

 30, 1876. 



[Communicated by Count Marschall, C.M.G.S., etc.] 



THE rocks along the Okande river are argillaceous slates, gneiss, 

 and mica-schists with garnets, intermixed with subordinate 

 bands of reddish-white quartz. The prevailing rock in the Ashkura 

 region is a coarse-grained granite, containing reddish- white, and 

 frequently large crystals of orthoclase, having bright cleavage- 

 planes, — oligoclase in smaller crystals, white with distinct binary 

 striation, — also biotite-mica in green or greenish-black plates, single 

 or agglomerated into small nodules, and amphibole in single, rather 

 large, black, tabular crystals. In several detached blocks the felspar 



