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 homy, 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. 1) jn/i4. C| VH. 5k 



4. Genus Purpura. PI. XIL 



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 coluraellar edge nearly straight, covered 

 with a callosity ; operculum horny, flat, nearly semicircular, with 

 faintly marked transverse striae. 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. pUcata. 



P. bufo. P. rustica. 



P. planospira. P. hystrix. 



P. carinifera. P. retusa. 



P. squamosa. 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. 



