376 



NORTH AMERICAN INDEX FOSSILS. 



Fig 



[677. Nothozoe ver7)iontana : «■, nearly circular valve ; /;, r, right and left valves 

 in quartzite. (After Walcott.) 



V. EcHiNOCARis Whitfield. 



Hinge short, the bivalve carapace suboval, broad in front, with 

 a free rostrum, not incurved behind, and with no posterolateral 

 spines ; a single S-shaped keel on each valve and sometimes a small 

 accessory ridge near the hinge ; surface punctate and pustulose ; 

 no longitudinal striations; of the body segments, six are exposed 

 and bear small spines on their surface and posterior margins ; telson 

 and its lateral spines (cercopods) of unequal size. Devonic. 

 10. E. punctata (Hall). (Fig. 1678.) Devonic. 



Large; carapace with short hinge area; oval valves marked by 

 a number of large, rounded nodes in anterior third ; with smooth 

 marginal rim and no pustules ; abdominal segments rather irregu- 



FiG. 1678. Echinocaris punctata^ complete, with the carapace slightly crushed, 

 X I. (After Beecher. ) 



lar, posterior one much longer than others which are roughly 

 nodose on their posterior margins; telson somewhat longer than 

 cercopods. 



Hamilton of New York. 

 II. E. socialis Beecher. (Fig. 1679.) Devonic. 



Carapace with anterior end rounded, making slightly more than 

 a rectangle with the hinge line ; posterior end produced, sharply 

 rounded ; marginal rim noded and surface marked with a series 



