01 s 



NEW YORK STATE MUSEUM 



Genus betrichia McCoy 

 Beyrichia dagon Clarke 



Plate 5, fig. 12-14 



Beyrichia dagon Clarke. U. S. Geol. Sur. Bui. 16. 1885. p. 29 

 This form is broadly ovate in outline, widest toward the rear, 

 the anterior being abruptly rounded. The valves are strongly 

 gibbous, specially toward the rear. Just in front of the middle 

 on either side a broad valley goes from top to bottom. In this 

 there rises a moderate node extending about halfway from top 

 to bottom, and as high as the shell outside the valley. The 

 shells run very uniform in size, a typical one measuring f mm 

 in lengtii. £ mm in hight and f mm in thickness. This form 

 is common at the Livonia salt shaft, and occurs sparingly at 

 Canandaigua lake and Moscow. 



Genus ento3Iis Jones 

 Entomis prosephina nov. 



Plate 5. fig. 10, 11 



This is represented by a single but finely preserved specimen. 

 The outline is broadly ovate, valves extremely gibbous, shell 

 punctate. Near the front there are two concentric lines as for a 

 beak. Just forward of the middle on each side is a deep sickle- 

 shaped depression. The lower anterior end is drawn out and 

 compressed into a plowlike, rounded projection. The measure- 

 ments are, hight % mmm, length 1% mm and thickness % mm. 

 The specimen is from Canandaigua lake. 



