PART II. MACROTRACHIA. — TKLLINID^. SGp 



the umbones are remote ; the ligament placed in an 

 external slit ; the lateral teeth very short and small, 

 and the cardinal teeth nearly obsolete. 



S< Sp/engleri. En. Meth. 252. f. 3. 



Hemimactra Sw. General form of Mactra ; but the 

 cardinal teeth entirely wanting ; cartilage internal^ 

 central, in a large triangular cavity ; lateral teeth ^, 

 distinct, lamellar^ striated : connected to the Glyct- 



. ?neri. 



H. gigantea Lam. v, 472. No. 1. graiidis Sw. Sp. Nov. 



Crassatella Lam. Shell solid, heavy, not gaping, more 

 or less rostrated ; hinge very thick ; cardinal teeth % 

 sub-ang-ular, striated, and placed on one side ; imme- 

 diately beneath the umbones is a triangular cartilage; 

 lateral teeth obsolete: representing Pawrfo/a, Trigonia, 

 Placuna, &c. 

 C. Kingicola Layn {Jig. ] 18. a.) rostrata. Sow. Man. f. 84. 



Glycimeris Lam. Oblong, transverse ; both extre- 

 mities gaping ; cardinal and lateral teeth entirely 

 wanting ; but the hinge margin very thick ; ligament 

 large, external : representing Solenimya, and con- 

 nected to Solen by Novaculina.* 



G. Siliqua. Sow. Gen. 4;^(%N^t^r&;ZX 



Family TELLINIDiE. Solid and close Bivalves. 



Shell never gaping t ; equivalve ; the margins thickened 

 and solid ; rarely covered with an epidermis ; cardinal 

 and lateral teeth well developed. 



SUB-FAM. 1. CYCLING. 



Animal generally fluviatile ; shells covered by an epi- 

 dermis. 



Cyclas:): Lam. Shell thin, transversely ovate, equila- 



• The four other sub-genera are unknown. t Except in Psammobia. 

 X Including Pisidum. 



