342 SHELLS AND SHELL-FISH. PART II. 



Canthidomus Sw. Spire generally short ; whorls co- 

 ronated with spines, or marked with longitudinal ribs; 

 base obtuse. 



F^rus. Moll. Melanop. pi. 2. costata. Sow. Gen. f. 3. 

 f. 9. 10.,pl. 1. 13,14,15. 



Melatoma Sw. Fusiform ; longitudinally 

 ribbed ; a deep sinus at the top of the 

 outer lip ; base contracted, channel wide.* 

 M. costata Sw. {Jig. 104.) 



Cerithidea. Clavate ; cerithiform ; aper- 

 ture sub-emarginate. 



Triphorus Desh. Shell small, slender, sub- 

 cylindrical ; spire long, of numerous 

 whorls ; aperture sinistral ; outer lip re- 

 flected over and united to the inner, but 

 leaving a circular opening. 



T. costata. Sow. Gen. f. 375. 



Cerithidea Sw. Shell light ; decollated ; outer lip semi- 

 circular, dilated by a flattened border ; aperture 

 emarginate. 

 C. lineolata. Griff. Cuv. 14. f. 4. fragilis, lb. 32. f. 12. 



Ceriphasia Sw. Cerithiform ; outer lip thin, dilated at 

 the base ; aperture small, slightly emarginate, without 

 any internal groove ; inner lip thin. 



C. sulcata Sw. (Jig. 38. p. 204.) 



Planaxis. Animal marine ; shell obovate ; inner lip 

 much thickened above ; pUlar flattened ; the base 

 with a small notch or sinus. 



P. semisulcatus Lam. Sow. Gen. f. 3. 



SuB-FAM. TURBIN.E. 



Animal marine ; shell solid, spiral ; aperture round or 

 oval, entire, sometimes toothed.t 



* Representing P/^M>-o<owrt, and united to Melafusus. 

 f Except certain types of Me/ampus, which appear amphibious ; and 

 others which have plaits and teeth on the aperture. 



