LAMELLIBRANCHIATA OF THE LOWER MARLS. 157 



and to have a greater excavation in front than the shell would indicate. 

 This is the result of a thickening which takes place opposite the beaks in 

 the shell, leaving the liinge-plate shelving more behind it, which produces 

 the beak in the casts further back. 



In the collection of the Academy of Natural Sciences of Philadelphia 

 the specimens which are marked in Mr. Conrad's handwriting Cyprimeria 

 Cretacea appear to be positively identical with those marked as of this spe- 

 cies. I have therefore cited that species as a synonym of this one, although 

 the original figure given in Vol. II, Journal Academy of Natural Sciences, 

 new series, PI. XLVI, Fig. 1 1 , would appear to be somewhat more elongated 

 than any of the specimens which I have seen. 



In regard to the generic relations of this shell there may not be any 

 real doubt, but it is quite certain that the pallial sinus is obsolete. Nor can 

 I say with certainty that I have seen a pallial sinus on any species from 

 New Jersey which has been referred to this genus, although it is usually 

 described as possessing such a feature, and is referred to a family which is 

 supposed to be composed of sinuopallial shells. The entire expression of 

 this shell in the interior is more that of an Astarta than of a Tellina, only 

 for the bending of the valves. 



Formation and locality. — The shells which I have used, and which 

 belong to the Academy of Natural Sciences of Philadelphia, are from the 

 micaceous clays of the Lower Mai-ls at Haddonfield, New Jersey. The cast 

 which I have figured is from Freehold, New Jersey, and is from the collec- 

 tion of the American Museum of Natural History, New York City. 



Cyprimeria densata. 



Plate XXII, Figs. 19-21. 



TeUina densata Conrad. J. A. N. Sci., Phil., 2d ser., Vol. TI, p. 275, PI. XXIV, Fig. 14 

 Bosinia densata (Con.) Gabb. Synopsis, p. 120. Meek, Check-list, p. 13. 

 D. donata (Con.) [by error for D. demata] Meek. Geol. Surv. N. J., 1868, p. 727. 



Cyprimeria densata Conrad. Am. Jour. Conch., Vol. II, p. 102. 



Not Dosinia densata Conrad. J. A. N. S. Phil., 2d ser.. Vol. Ill, p. 72.5, PI. XXXIV, 

 Fig. 13 ( = C alta Con. Kerr's Eept. Geol. N. C, Appendix, p. 27). 



Shell large, transversely ellii^tical, with the posterior end broadly and 

 squarely truncate. Valves moderately convex, the right more prominently 



