216 MANUAL OF THE MOLLUSC A. 



has observed that B. Umhosum, $ has the teeth seven cusped, 

 while in the females they are six cusped. 



Distribution^ 106 species. West Indies, Mediterranean, West 

 Africa, India, Australia, South Pacific, Western America. 



Fossil, 30 species, TJ. chalk — . Prance. 



TUHBINELLA, Lam. 



Etymology, diminutive of turho, a top. 



Type, T. pyrum. PI. V., Pig. 2. 



Shell thick ; sj^ire short ; columella with several transverse 

 folds. Operculum claw-shaped. Pig. YO. The chank-shell 

 {T. pyrum) is carved by the Cingalese, and reversed varieties of 

 it, from which the priests administer medicine, are held sacred. 



Distribution, 70 species. West Indies, South America, Africa, 

 Ceylon, Philippines, Pacific, Western America. 



Fossil, 20 species. Miocene — . 



Sub-genera, Cynodonta (Schum.), T. cotnigera. PI. y.,Fig. 3. 



Latirus (Montfort), T. gilbula. PI. V., Fig. 4. 



Lagena (Schum.), T. Smaragdula, L. species. Northern 

 Australia. 



Cancellabia, Lam. 



Etymology, cancellatus, cross-barred. 



Type, C. reticulata. PL Y., Pig. 5. 



Shell cancellated ; aperture chanelled in front ; columella with 

 several strong oblique folds ; no operculum. The animals are 

 vegetable feeders. (Desh.)* 



Distribution, 71 species. West Indies, Mediterranean, West 

 Africa, India, China, California. 



Fossil, 60 species. Up. Chalk — •. Britain, Franco, &c. 



Admete (viridula) is a boreal form of Cancellaria, without 

 plaits. 1 



DiBAPHUS, Phi. 



Synonym, conohelix edentulus. (Sw.) Shell subcylindrical, 

 spire acute ; aperture narrow, linear, edentulous, excised at tho 

 base; lip thickened, rectilinear, rounded and abbreviated below. 



TmcHOTROPis, Broderip, 1829. 



Etymology, Thrix (trichos), hair, and tropis, keel. 

 Type, T. borealis, PI. VI., Fig. 8. (= ? Admete, Phil., no 

 operculum). 



* Cajicellana and trichotropis form a sai?i" natural family cODuectecl with cerithiwlfi 

 and strombidce. 



