388 MR. E. A. SMITH ON THE [Apr. 18, 
teriorly, with the arcuate margin red, and reddish on the inner surface, 
with two pale rays from the nucleus, one central and the other sub- 
marginal, the extreme edge being blackish. In all these respects it 
coincides with that of N. gagates, Lamarck, from the Mauritius ; 
and the terminal processes are similar in both forms. Von Martens’s 
conjecture that the species might belong to WV. retifera, Benson 
(Conch. Cab. p. 283), is not to be wondered at, considering the 
briefness of Reeve’s description, and the fact of only the back of the 
shell being figured. 
B. CONCHIFERA. 
CoRBICULA MADAGASCARIENSIS, sp. nov. (Plate XXII. figs. 
25-27.) 
Shell a little inequilateral, rounded and narrow in front, much 
broader, squarish, and subtruncate posteriorly, arcuate along the 
ventral margin, finely concentrically striated; yellowish, greenish 
down the posterior side. Umbones a little prominent, incurved, 
situated a little anteriorly. Interior lilac, with two or three rather 
distant concentric purple zones, stained with dark purple down the 
posterior side, and with a smaller stain of the same colour at the an- 
terior side. 
Length 114 millim., width 14, diameter 7. 
Hab. Twenty miles from Antananarivo (Johnson). 
The concentric striz are deep and regular upon the umbones ; but 
towards the ventral margin they become less regular and finer, and 
in front are rather more strongly developed than towards the pos- 
terior side. This is the first record of the genus in Madagascar ; 
and I have not been able to associate the species with any of the forms 
described from the adjacent continent. 
SPH&HRIUM MADAGASCARIENSE, Tristram. 
Spherium madagascariense, Tristram, Proc. Zool. Soc. 1863, p.61; 
Sowerby, Conch. Icon. pl. iii. f. 22, bad ! 
Hab. Two days west of Antananarivo (T'ristram) ; about 20 miles 
from the capital (Johnson); Betsileo (Cowan). 
This species is scarcely if at all different from S. capense of Krauss, 
and is mainly distinguished by difference in locality. The slight 
compression of the valves towards the circumference, remarked upon 
by Tristram, is not constant in all specimens, some exhibiting it ina 
comparatively decided manner, whilst others are rounded at that part 
just like the South-African form. 
LIMOSINA FERRUGINEA, Krauss. 
Cyclas ferruginea, Krauss, Sudafr. Moll. p. 7, pl. i. f. 7; Clessin 
(as Limosina), Conch. Cab. p. 247, pl. 46. f. 1-4; Sowerby (as 
Spherium), Conch. Icon. f. 47, not good ! 
Hab. The river Knysna, South Africa (Krauss). About 20 
miles from Antananarivo (Johnson). Also Mauritius (Brit. Mus.). 
