EXPLANATION OF PLATE XV. 



Mactka i.atekalis Say (p. 82). 



1, 2. Opposite sides of a right valve. 



3. Enlargement of the hinge, showing tlie structure. 



KAN(ilA (rEHissdiioN) MiNOl! ('ouriid (p. 84). 



4,5. Opposite views of a right valve, twice enlarged, 

 fi. Further enlargement of the hinge. 



Syndosmya NiTcrr.oiDES Conrad (p. 81). 



7.x. Opposite views of a right valve, imperfect at the posti'niir end, twice enlarged. 

 !t. I'uither enlargement of the hinge. 



Mactra (Schi/.(H>ks.via) i>emmbis Conrad (p. H2). 



10. Copy of Mr. Conra-d's (igure of this species given in his Miocene Fobs., PI. xv, fig. 1. 



COKBULA SUBCONTRACTA Whitf. (p. 88). 



11, 12. Two views of a right valve, enlarged. 



13, 14. Upper and cardinal views of a specimen retaining the valves in position, enlarged. 



CoRHiLA ELEVATA Conrad (p. 86). 



ir>. Enlarged view of a right valve. 

 ir>. Interior of a right valve, natural size. 

 17, 18, 19. Three views of a specimen retaining the valves in position ; twice enlarged. 



CouniM.A IDONEA Conrad (p. 8K). 



20. Copy of Conviid's figure, Miocene Fossils, PI. x, lig. ti; noneof the New Jersey speci- 

 mens lieing surticiently perfect to illustrate. 



