CONCHOLOGY. 139 
Shell. Oval or subglobular, thick, armed with points and with 
a depressed spire ; aperture narrow, elongated, notched, sometimes 
canaliculated anteriorly and digitated exteriorly ; left edge more 
or less callous; operculum horny, oval, and transverse. Found 
in the Indian seas. Nine living species. 
Ricinula horrida. Ricinula clathrata. 
R. arachnoidea. R. miticula. 
R. digitata. R. pisolina. 
R. aspera. R. morus. 
R. mutica. 
4, Genus Purpura. Pl. XII. 
Animal. As above. 
Shell. Oval, tuberculated, thick; spire short, the last whorl 
much larger than all the others united; aperture oval, greatly 
dilated, terminated anteriorly by a short, oblique canal notched 
at the extremity; the columellar edge nearly straight, covered 
with a callosity ; operculum horny, fiat, nearly semicircular, with 
faintly marked transverse strie. Found in the European and 
South American seas. Sixty-two species. 
Purpura Persica. Purpura Francolinus. 
P. columellaria. P. cruentata. 
P. armigera. P. lagenaria. 
P. undata. P. plicata. 
P. bufo. P. rustica. 
P, planospira. P. hystrix. 
P. carinifera. P. retusa. 
P. syuamosa. P, fasciolaris. 
P. sertum. P. nucleus. 
P, ligata. P. subrostrata. 
P. imbricata. P. patula. 
P. bicostalis. P. consul. 
P. thiarella. P. hippocastana, 
P. echinulata. P. mancinella. 
P. unifascialis. P. neritoides. 
P. clavus, P. coronata. 
P. bizonalis, P. sacella. 
