INVERTEBRATE PALEONTOLOGY. 193 



teeth and the general form of the shell. The distinctions between these 



groups may be briefly stated as follows : 



1. TELLiNA, Linn, (typical). 



Shell transversely elongate-oval, with well-developed cardinal 

 and lateral hinge-teeth. — (Type as already stated.) 



2. tellinella, Gray. 



Shell more or less narrowly elongated, with posterior side 

 rostrated or subrostrated ; hinge with two lateral teeth in one valve, 

 and none (or only very obscurely-developed laterals) in the other. — 

 T. virgata, Linn. 



3. FERONiEODERMA (Poli), Morcll. 



Shell oval, with posterior side not much produced or distinctly 

 rostrated ; hinge with lateral teeth in one valve. — T. punicea, Born. 



4. mcera, H. and A. Adams (z= Donacilla, Gray ; not Lam.). 



Posterior side very short and cuneate ; hinge with two lateral 

 teeth in one valve. — T. donacina, Linn. 



5. pal^omcera, Stoliczka. 



Shell much as in the last, with one anterior lateral, long, lamelli- 

 f'orm tooth in each valve, that of the right being bifid, and that of the 

 left entire ; and no distinctly-developed posterior cardinal tooth in 

 either valve ; lateral teeth less distinct in the left than the right 

 valve. — T. strigata, Goldfuss. 



6. phylloda, Schumacher. 



Shell transversely oblong, much compressed, with posterior side 

 narrowed, angular, and carinate; cardinal teeth divergent and com- 

 pressed; one lateral tooth in one valve. — T. foliacea, Linn. 



7. angulus, Schumacher (— Tellinula, Chem., FabuUna, Gray). 



Shell oblong or oval ; posterior side more or less angular; and 

 hinge with only one lateral tooth in one valve. — T. exilis, Lam. 



8. tellinides, Lam. 



Shell transversely oval, without a posterior fold; hinge with one 



approximate lateral tooth. — T. timorensis, Lam. 

 25 h 



