24 



I observe no species in Deshayes's most useful, though crude, 

 monograph, which at all resembles it in aspect. Its dentition fixes 

 it in Cyrena proper : the hinge-margin is strong, and the cardinal 

 teeth of the right valve peculiarly large. The inner disk, beneath 

 the u in bones, has a redder tint ; there is neither a lunule, nor any 

 indication of an umbonal ridge. 



Siphonaria brunnea. S. testa solida, obovali, pyramidato- 

 subdcpressa, vel omnino brunnea, vel (in junioribus) costarum 

 brunnearum interstitiis subalbidis ; costis permultis parvis 

 (haud autem Jiliformibus) saturatioribus subrotundatis radiata; 

 vertice albido, subcentrali, subacute, aliquantulum adunco ; 

 lateribus cequalibus ; angido siphonali satis conspicuo ; super- 

 ficie interna albida, vix ad marginem crenatum brunneo colore 

 articulata. 

 Long. 1(H lin., lat. 9 lin. 

 Hub. In insula Bermuda. Mus. Cuming. 



The only four examples known to me are somewhat (though 

 slightly) rubbed, so that it is difficult to say whether the moderately 

 raised ribs are smooth or nodosely crenated. From the prevalence 

 of interstitial costellse, especially posteriorly, the number of decided 

 ribs (none of which are peculiarly conspicuous) seems variable with 

 age : the range is apparently from thirty to forty. 



S. CAiiBO. S. testa solida, sub symmetrica, rotundato-ovali, pyra- 

 midato-subdepressa, extus intusque ubique picea ; costis per- 

 midtis, haud autem confertis, subnodosis, et satis elevatis ra- 

 diata : vertice centrali, recto, simplici : lateribus cequalibus : 

 margine crenato : impressione siphonali intus (vix etiam extus) 

 conspicua. 

 Long. 1 1 lin., lat. 9% lin. 



Hab. ? Mus. Cuming. 



The only individual known to me might pass externally for S. 

 brunnea, and internally for a dwarf characteristica. From the 

 former it is readily distinguished by the uniform and intense dark- 

 ness of its somewhat bronzed interior, from the latter by its very 

 numerous and close-set ribs, which are apparently equal in breadth, 

 and more or less blunt. 



S. parma. S. testa obovata, pyramidato-depressa, solida, sub- 

 symmetrica, albida, costis permidtis confertis subcequalibus 

 rotundatis muticis (vix autem Icevigatis) radiata; interstitiis 

 linearibus castaneis : lateribus cequalibus : vertice centrali, 

 simplici, subacuto : costa siphonifera duplici satis conspicua : 

 pagina interna superne ferruginea, ad marginem crenatum 

 albida. 



Long. 8^ lin., lat. 8 lin. 



Hab. In Africa Occidentals Mus. Cuming. 



The only individual I have seen is disposed to be much dilated 

 posteriorly, and is livid around the prominent umbo : these charac- 



