Dentition of Pulmonale Mollushs. 109 



Marginals quadrate, of equal width and height, with two short, wide, bluut, 

 round cusps, the inner one slightly the larger. 



Thelidomus lima, Fer. Porto Rico. Mr. K. Swift. 



Jaw arcuate, ends blunt; anterior surface with seven stout ribs; a strong- 

 muscular attachment. 



No lingual membrane examined. 



Thelidomus Jamaicensis, Chemn. Jamaica. V. P. Parkhurst. 



The species is placed in Liochila by von Martens, but Mr. Bland places it 

 in this genus. 



Jaw thick, arcuate, ends attenuated ; anterior surface with 14 decided 

 but unequal ribs, irregularly disposed and denticulating either margin. 



Lingual membrane (PI. VIII, fig. H) long and narrow, with 41-1-41 teeth; 

 there are no distinct side cusps and cuttting points on the centrals and inner 

 laterals. 



Thelidomus provisoria, Pfr. New Providence, Bahamas. Gov. 

 Rawson. 



Jaw very slightly arcuate, wide, low, of equal height throughout to its 

 blunt ends; anterior surface with 10-15 ribs, separated by irregular intervals, 

 not always reaching the cutting edge, which has a broad, blunt, median 

 projection. 



Lingual membrane (PI. VIII, fig. I) with 40-1-40 teeth ; the centrals and 

 laterals have a distinct side cutting point. 



Eurycratera. 



Eurycratera angulata, Fer. Porto Rico. Mr. R. Swift. 



Jaw stout, dark claret-colored, low, wide, ends blunt; about seven very 

 wide, very crowded ribs, bluntly denticulating either margin. 



Lingual membrane (PI. VIII, fig. J) ; central and laterals with distinct 

 side cutting points. 



Eurycratera crispata, Fer. San Domingo. Dr. Newcomb. 



Jaw thick, arcuate, ends blunt ; anterior surface with ten stout ribs. 



Lingual membrane (PI. VIII, fig. K). Centrals and laterals with the 

 upper margin of the base of attachment produced into angles as below, with 

 distinct side cutting point; middle cutting point of centrals and inner cutting 

 point of laterals greatly produced. 



PoBydomes. 



No jaw of this genus examined. 



Polydontes Luquillensis, Sliuttl. 



Lingual membrane (PL VIII, fig. L) as usual in the Ilelitidcc. Centrals 

 tricuspid, laterals bicuspid; cusps wtih long, sharp cutting points, extend- 



