MOLLUSCA. 559 



Formation and locality. Merchantville clay, near Matawan 

 (101) Cross wicks (Conrad). 



Geographic distribution. New Jersey. 



Crassate Mites littoralis (Conrad). 

 Plate LXL, Pigs. 9-10. 



1869. Crassatella littoralis Con., Am. Jour. Conch., vol. 5, p. 



41, pi. i, fig. 3. 

 1886. Crassatella conradi Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. $., vol. 9), p. 209, pi. 28, figs. 1-5. 

 1886. Crassatella littoralis Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. S., vol. 9), p. 212, pi. 28, figs. 6-7. 



Description. The dimensions of an incomplete right valve, 

 upon which the shell is partially preserved, are: length, 35 mm.; 

 height, 29 mm. ; convexity, 8 mm. Shell subovate in outline, with 

 moderately convex valves; be.aks situated at about the anterior 

 third of the shell. Antero-cardinal margin sloping steeply down- 

 ward from the beak, the anterior margin rounding regularly 

 into the basal margin; basal margin regularly convex; postero- 

 basal extremity rather abruptly rounding; posterior margin 

 gently convex, nearly vertically or a little obliquely subtruncate; 

 post-cardinal margin sloping backward to the posterior hinge 

 extremity; greatest height of the shell opposite the beaks. A 

 more or less obscure, rather broadly rounded umbonal ridge 

 passes from the beak to the postero-basal angle. Surface of the 

 shell marked with somewhat regular and rather strong con- 

 centric lines of growth, which seem to be most strongly marked 

 anteriorly. Shell substance rather thick, and when the outer 

 surface is exfoliated a series of more or less conspicuous radiat- 

 ing markings can be seen. Inner surface of the free margin of 

 the shell crenate. In the internal casts, the usual condition of the 

 species, the beaks are prominent, highly elevated, and rather dis- 

 tant, the muscular and pallial impressions are of moderate 

 strength; the umbonal ridge is variable, being subangular or 

 broadly rounded in some individuals, and in others scarcely dif- 

 ferentiated at all in the casts. 



