CONCHYLI A— D/THYi?^. 51. ^35 



Shell about a quarter of an inch in diameter, whitish, with the 

 heak terminal : the under valve has the perforation entire all round, 

 and produced into a raised cylindrical tube. The plug of attach- 

 ment is tendinous. 



51. TEREBRATULA— Bi2t7G[7/Ei2E. 



Test ovata, intsquivalvis, pedicello tendineo jixa ; valvd superiori um- 

 bone producto, perforata jeu emarginato ; inferiori ramis duobus, 

 scBpe ramulosis, e disco interno protensis. Cardo dentibus duobus : 

 lateralibus nullis. Ligamentum internum. 



Shell oval, inequivalve, fixed by a tendinous pedicle ; the upper valve 

 with the beak produced, and perforated or emarginate ; the under 

 valve with two elongated projections issuing from the internal 

 disk, and which are sometimes variously branched. Hinge with 

 two teeth : lateral teeth none. Ligament internal. 



This genus is also parasitical, being fixed to submarine substances 

 by a tough short stalk, which issues from the aperture at the 

 termination of the extended beak in the upper valve. The 

 internal structure of the under valve, independently of the strong 

 joint -like primary teeth, exhibits a remarkable apparatus for 



2h 2 



