GASTEROPODA. 



69 



a whorl from each other, longitudinally united, and form- 

 ing a ridge on each side of the shell ; canal 

 either long or short ; a sinus, or short canal 

 at the upper part of the aperture. Animal 

 like that of Triton. — 50 species * ; also 

 fossil. 



From the Indian and American Oceans, 

 and the Mediterranean Sea. Some of the 

 species are very handsome shells, the canal scmeiia crumena. 

 at the upper part of the aperture, and the 

 peculiar situation of the varices, being their great charac- 

 teristics. 



Purpura. Brug. — Shell oval, thick, either smooth or 

 tuberculated ; spire short; aperture large 

 and notched ; left lip depressed and flattened ; 

 right lip generally toothed or wrinkled ; oper- 

 culum thin, half-moon-shaped, and horny. 

 Animal, with a broad lunate flattened head, 

 flanked by two tentacula, which have broad 

 and stout bases, composed of the shortened 

 eye pedicles, united with the tentacles for Purpura 



" A columellaris. 



nearly half their length; beyond the eyes the 

 tentacles are stoutly subulate ; proboscis reticulate, mode- 

 rately long; tongue long, armed with teeth, which are 

 ranged three in a row, the middle or axile one broadly 

 quadrate and tridentate, the laterals claw-shaped; jaws 

 linear, corneous ; mantle lax, produced into a short siphon, 

 which is rarely projected far beyond the canal of the shell ; 

 branchial plumes two ; foot ovate, oblong, or subquadrate ; 

 posteriority obtuse, anteriority emarginate.f — 80 species %\ 

 also fossil. 



The Purpura is found most abundantly in warm seas, 



* Reeve's Iconica. 



t British Moll. 



P 3 , 



\ Iconien. 



