MOLLUSCA. 585 



prominence; central and anterior portions of the shell marked 

 by concentric lines of growth only. 



Remarks. Both of the species described by Whitfield from 

 New Jersey as Cardium perelongatumi and Pachycardium bur- 

 lingtonense, are certainly internal casts of the shell described by 

 Conrad from Mississippi as Cafdium spillmani, the example to 

 which the last of the two names was applied being an exception- 

 ally broad specimen. The species is for the most part restricted 

 to the Navesink marl, where it attains its maximum size. The 

 specimens which have been rarely noticed in the Merchantville 

 clay are usually small, although Whitfield's P. burlingtonense is 

 a very large example. The internal casts, in which condition the 

 species usually occurs, have some resemblance to those of the 

 species described in this report as C. kummeli, but they are 

 usually larger than that species, the beaks have more of a for- 

 ward curvature, the anterior portion of the hinge-line is longer 

 and extends further down towards the base of the shell, the 

 anterior muscular impressions are lower in position, and the shell 

 is radiately ribbed posteriorly. When the shell itself, with its 

 external markings is preserved, it is not possible to confuse the 

 two species. 



Formation and locality. Merchantville clay-marl (rare), near 

 Matawan (ioo 4 , 101); Navesink marl, Atlantic Highlands 

 (108), near Walnford (i48 2 ), Crosswicks Creek (i47 3 , 147*, 

 195), near Jacobstown (150). 



Geographic distribution. New Jersey, Alabama, Mississippi, 

 Texas, Oklahoma. 



Cardium kummeli n. sp. 

 Plate LXVL, Figs. 1-3. 



Description. The dimensions of a rather small internal cast 

 of a right valve are : height, 45 mm. ; width, 34 mm. ; convexity, 

 17.5 mm. Large individuals sometimes attain a height of 70 

 mm. or more. Shell subovate in lateral view, cordate in end view. 

 Beaks of the internal casts greatly elevated above the hinge-line, 

 pointed and incurved. Hinge-line arcuate; anterior margin 

 regularly rounded from the extremity of the hinge-line to the 



