On Mollusca from South Africa. 599 
canals, 21-23 z, 1 or 14 between lateral line and root of 
ventral. Uniform brownish above, silvery white below. 
Total length 105 to 225 millim. 
One specimen from Lagos (ZH. 7. Ussher) and four from 
the Gold Coast (R. B. N. Walker). These specimens have 
been referred to A. macrolepidotus by Dr. Giinther. Stein- 
dachner’s A. macrolepidotus from Liberia (Notes Leyd. Mus. 
xvi. 1894, p. 63) probably belongs to the same species. 
The four closely allied Alestes, characterized by very large 
scales and the very posterior position of the dorsal fin, may 
be distinguished as follows :— 
A. The distance between the end of the snout and the occiput much 
greater than the width of the head; snout projecting con- 
siderably beyond the lower jaw in the adult. 
Anal 15-17; lat. 1. 22-26; depth of body 
32 to 44 times in total length ........ A, macrolepidotus, C. & V. 
B. The distance between the end of the snout and the occiput not or 
but little greater than the width of the head; snout projecting 
but slightly beyond the lower jaw. 
Anal 13-14; lat. 1. 24-27; depth of body 33 
to 32 times in total length............ A. grandisquamis, Blev. 
Anal 16-18; lat. 1. 21-23; depth of body 2¢ 
fold times in total length ............ A. brevis, Blgr. 
Anal 15-16; lat. 1. 28-29; depth of body 35 
to 4 times in total length ............ A. Batestt, Blev. 
LXI.— Descriptions of Thirty-one Terrestrial and Fluviatile 
Mollusca from South Africa. By JamMEs Cosmo MELVILL, 
M.A., F.L.S., and Joun Henry Ponsonsy, F.Z.5. 
[Plates XKXI. & XXXIL] 
AFTER an interval of more than two years * we are enabled 
to offer another contribution (the seventeenth) towards the 
elucidation of the non-marine Molluscan fauna of South 
Africa, in which are included descriptions of several species 
of Ennea and Trachycystis—T. scolopendra, perhaps, being 
the most remarkable Helicoid yet reported from this region. 
An Achatina, Buliminus, Planorbis, a most interesting 
Fauaulus, a Tropidophora, and a Chondrocyclus are, amongst 
* Ann. & Mag. Nat. Hist, ser. 7 (Oct, 1901), vol. viii. pp. 315 sqq. 
