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 antennse, 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 antennse 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 desci'ibed 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 
forme'r appear two large black oval bodies, United at their bases, 
which may be the ovaries. 
The author carefully notes the differences existmg between the 
structure of the Organs as exhibited in Falceocypris and that of tbe 
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 Organization is con- 
cerned, is the more interesting when the immense iuterval of time 
by which their periods of existence are separated is taken into con- 
sideration. B.B.W. 
III. — Geological Notes on some Pakts of West Tropical Africa. 
By D. 0 . Leng. From the Bep. Imp. Geol. Instit. Vienna, Jutie 
30 , 1876 . 
[Communieated by Count Marschaxl, C.M.G.S., etc ] 
T HE 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 
