NATURAL SCIENCES OF PHILADELPHIA. 139 



DESCRIPTIONS OF A NEW FOSSIL SHELL FROM PERU. 

 BY T. A. CONRAD. 



OSTREA, Lin. 

 0. callacta, PI. 22, fig. 1. 



Suborbicular, compressed, profoundly and equally plicated on 

 both valves; folds rounded, wide, elevated, about 8 in number; 

 upper valve concave on the umbo, entire towards the apex, eon- 

 centric lines thick and prominent. 



Locality. " This shell was picked up at the confluence of the 

 Pachitea and Pichis rivers, which flow through the Pam pa del 

 Sacramento in Eastern Peru." Dr. Gait. 



Having seen one specimen only, it may be found to vary in the 

 number of ribs. 



Dr. Gait brought this fine specimen from Peru and presented 

 it to the Academy of Natural Sciences. 



It probably comes from the Pebas group. 



ACICULA ? Risso. 



A. PI. 22. fig. 2. 



This appears to be a young shell allied to the Glandina forms. 

 As there is one specimen only, and that very 3 r oung, I am unable 

 to state whether it be undescribed or not. Prof. Orton found it 

 at Villa Delia. 



