498 CRETACEOUS PALEONTOEOGY. 



more or less distinct radiating costse. Lower valve flat, concave 

 or convex, often irregular in contour, the perforation rather 

 large and situated near or at some distance from the margin. 



Remarks. — -In common with all members of this genus, this 

 species is. exceedingly irregular in form, and also exhibits con- 

 siderable variation in its surface markings. The specimens 

 described by Morton under twO' specific names, argentaria and 

 tellinoides, are quite certainly members of a single species, and 

 ■argentaria being the prior name, must be adopted for the species. 

 Whitfield restricted the name A. argentaria to a single individual 

 studied by him, which differed 'from the common Anomia of 

 the New Jersey faunas, called by him A. tellinoides, in its more 

 regular concentric lines of growth and in its regular and con- 

 spicuous radiating costse, and in the position of the apex of 

 the upper valve being not so nearly marginal. The strong radi- 

 ating costse o.f this specimen are somewhat unusual, although 

 specimens preserving the shells not uncommonly exhibit traces 

 of such markings, but the other characters noted are often met 

 with among specimens without the radiating markings. This 

 specimen is probably not specifically distinct from the other 

 members of the genus in the New Jersey faunas, although it 

 may possibly be a representative of Gabb's A. argentaria var. 

 ornata} 



Whitfield's figure 9 on plate IV. of his monograph, is not an 

 Anomia at all, but is a shell of Ostrea plumosa, its designation 

 as Anomia argentaria in the explanation of the plate was doubt- 

 less not SO' intended, since in the description of that species, as 

 interpreted by that author, it is definitely stated that only a 

 single individual had been observed. 



The shells which Whitfield has identified as Diploschiza cre- 

 tacea Con., seem tO' be nothing more than more strongly con- 

 vex individuals of Anomia argentaria. There is certainly no 

 sufficient basis for the genus Diploscliiza, and Conrad's types of 

 his species seem to have no characters to separate them from 

 Morton's species. A specimen with the shell perfectly preserved, 

 from the Navesink marl near Crawfords Corners, is strongly 



'Proc. Acad. Nat. Sci. Phil. (1876), p. 320. 



