140 



NEW YORK STATE MUSEUM 



Ceratocephala robinia nov. 



Plate 3, figures 9-11 



In the fauna of the Oriskany of New York I have noted the presence 

 of fragments of this genus which have been referred by me to C. (A c i d - 

 a s p i s) t u b e r c u 1 a t a Conrad, which is originally and typically from the 

 Helderbergian. Nothing is known of this Oriskany form except the cra- 

 nidia. There occurs in the Grande Greve limestones a form known from 

 various parts and one nearly entire specimen, which attains much larger 

 proportions than C. tuberculata and yet is allied to both that species 

 and the C. callicephala from the Onondaga limestone. Placing these 

 species in comparison we may find the distinctive characters expressed as 

 follows : 





C. tuberculata 



C. callicephala 



C. robinia 



Size 



Small 



Medium 



Large 



Neck ring 



With short stout spine 



With small spine 



With longer, stout and 

 somewhat curved 

 spine 



Thoracic segments 



Pygidium 

 ist spines 



Finely tubercled 

 Moderately long 



Regularly and coarsely 

 tubercled 



Slender and longer 

 than 2nd pair 



Coarsely tubercled 

 Very short 



2d spines 



Much longer 



Shorter than ist pair 



Longer than ist pair 



3d spines 



Large, stout and twice 

 the length of 2d pair 



Not conspicuously the 

 largest of the series 



Sharp and slender, 

 longest 



4th spines 



Very shoTt 



Relatively long and 

 slender 



Sharp and slender more 

 than yo, the length of 

 3d pair 



Surface 



Strongly tubercled 



Tubercled 



No tubercles 



These differences will be found to pertain chiefly to minor features but 

 we conclude that there is in the Gaspe specimens a distinction from these 

 allies in time and structure which is clearly defined and significant in the 



