Hinges of BritiJJj Bivalve Shells. 1 69 



if we are to jutlge by comparifon, it more pro- 

 perly belongs to that genus. 

 The hinge of the V. craja is very plain and fimple, 

 confifting of a grooved central tooth and two 

 others, which are remote. One valve, however, 

 has hardly the appearance of remote teeth, though 

 the central tooth in both is equally ftrong. 



undata. Pern. Br. Zool. No. 5 1. t. 5$. f. ^i. 



Tab. XVII. Fig. 17, 18. 

 The hinge of the F. undata has a fmall central tooth 

 fituated under the beak of the fhell, which fits into 

 a triangular cavity in the oppofite valve. A deep 

 fulcus runs from the beak in the direction of the 

 cartilage Hope. 



ARCA. 



Glycymeris. Linn. Syjl. Kat. ed, Gmel. i. />.'33i3. Penn. Br. Zool. No. 5 8. 

 /, 58./. 58. Da Cojl. Br. Conch. p. 168. /. 11./ 2. 3. 

 JJJi. Conch, t. 278. f. 82. Chemn. Conch. 7. /. 57. 



/ 564- 



Tab. XVIII. Fig. i, 2. 



" The hinge of the .d^ca Glycymeris is femicircular, 

 and on each fide fet with a curved row of flrong 

 tranfverfe teeth, generally from five to tea on each 

 fide." 



This is Da Cofta's defcription, and is fo far juft; but 



he tells us that the centre of the hinge is quite 



Vol. VL Z fmooth, 



I 



