PART II. MACROTRACHIA. — TRLLIiVID^. 36^ 



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. Sprengleri. 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 Glycu- 

 neri. 

 H. gigantea. Lam. v. 472. No. 1. grandis Sw. Sp. Nov. 



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

 or less rostrated ; hinge very thick ; cardinal teeth |- 

 sub-angTilar, striated, and placed on one side ; imme- 

 diately beneath the umbones is a triangular cartilage; 

 lateral teeth obsolete: representing Pa wrfora, Trigonia, 

 Placuna, Szc. 

 C Kingicola Lam {fig. 1 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, {fig. 118. 6, c.) 



Family TELLINIDiE. Solid and dose 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. 



CyclasJ Lam. Shell thin, transversely ovate, equila- 



* The four other sub-genera are unknown. f Except in Psammobia. 

 X Including PisiduTn. 



B B 



