58 CRETACEOUS GROUP 



entire specimen, nor, indeed, one sufficiently perfect to 

 figure. It was found near Arneytown, New Jersey, by 

 Mr. Conrad. 



3. P. venustus, (S. G. M.) PL y, fig. 7. 



Specific character. Orbicular, thin, depressed, with fifteen 

 or twenty double costce, those on the lower valve delicately 

 beaded. 



Diameter, about half an inch. 



Found with the preceding species. 



4. P. anatipes, (S. G. M.) PL v. fig. 4. 



Specific character. Suborbicular, flattened, with four broad, 

 convex ribs, longitudinally striated ; at the sides larger striae re- 

 place the ribs. 



Diameter, more than half an inch. 



I have seen but one imperfect individual of this species, 

 which is figured on the annexed plate \ it was obtained 

 from a mass of Nummulite limestone, from Claiborne, 

 Alabama. 



5. P. perplanus, (S. G. M.) PL v, fig. 5, and pi. xv, 

 fig. 8. 



Specific character. Orbicular, somewhat flattened, with about 

 twenty small, simple costas, trans ver.sely striated. 



Diameter, from three-fourths of an inch to an inch and a 

 quarter. 



Occurs with the preceding species. 



6. P. calvatus, (S. G. M.) PL x, fig. 3. 



Specific character. Orbicular, depressed, smooth, thin, with 

 a few obsolete radiating lines. 

 Diameter three-fourths of an inch. 



