CONC'HYLIA— D/Ff/l/J^. 3 Jl? 



collected from the fragment were all of the same size, and all 

 distinguished by tlie strong conical tooth on the margin above 

 the hinge, pointing in a rather oblique direction. 



3. GAHTROCUJE^ A— SPEJVGLEti. 



Testa transversa, ovata, rsquivalvis, inatquilateraUs , hiatu 

 tnaximo. Cardo dente tmico transversa sublamiuato oltso- 



letn, in utrdque valvd : lateralibus nullis. Ligatnentnm 



externum. 



Shell transverse, oval, equivalve, inequilateral, with a vast 



opening. Hinge with a single transverse somewhat laminar 



obscure tooth in each valve: lateral teeth none. Liofament 



external. 



In its habits this genus approaches very near to that of the 

 Pholas, living in the interior of rocks and stones covered by the 

 sea, where it forms an outer testaceous coat, in which tiie shell 

 itself is imbedded, surrounded by a slimy mucus: and this outer 

 case, which is formed upon the inner surface of the decomposed 

 rock, is quite smooth, extending beyond the rock itself, and is 

 partly divided at the end, like the tube of the Teredo navalis, fbi- 

 the protrusion of the two terminal lobes of the animal. In the 

 middle of the wide opening of the shell the animal is furnished 



D 



