110 NEW YORK STATE MUSEUM 



or the adult condition of the fossils under discussion. For the 

 last named the posterior moiety of the hinge is straight and 

 slopes downward. The node in most cases persists throughout 

 the stages of growth, and, though a feature which has not before 

 been recorded among the Estherias, it is, I take it, such a struc- 

 ture as one might expect to meet with in these phyllopods; such 

 a character as is so generally present in the Ostracoda and 

 Phyllocarida. 



The concentric ridges have an imbricating form, abrupt on 

 their posterior and gradual on their anterior slope, and both 

 ridges and interspaces are alike covered by fine, elevated 

 anastomosing lines departing somewhat radially from the um- 

 bonal region. The first impression made by these wrinkles is 

 that they are ridges of lateral crushing, but no specimen affords 

 any evidence of distortion. These ornamental lines are much 

 more conspicuous on the young shells but are visible even on 

 the adult shell where the concentric growth lines have become 

 crowded. 



The structure of this species seems to enforce a suggestion 

 which has previously been made that we are probably encourag- 

 ing misconception by permitting these ancient phyllopods to pass 

 under the name E s t h e r i a, whose type forms all pertain to 

 the existing fauna. 



