PLATE XXX. 



ECHINOCARIS SOCIALIS. 



I'age 171. 

 Fig. 1. A very young, entire iiMliviiln.il representing the earliest stage of growth observed. 



Chemung group. Warren, Warr ;„. 



Fig. •-'. A young individual in whirl, the abdomen is benl dorsally. 



Chemung gi-oup. Warren, Warren county, Pennsylvania. 



Fi -- :! - A " fixi le with the valves •• | and the abdomen protruding from the anterior margin of 



tin' carapace. 



Chemung group. Warren, Warren county, P unia. 



Fig. 4. An individual with the valves expanded and the abdomen closelj curved around 11." posterioi 

 margin of the left valVe. 



Chemung igrou|). Warren; Warr Pennsylvania. 



Pig. 5. The expanded valves of a larger iridividual. 



Chemung group. Warren, Warren county, Pennsylvania. 



Pig. G. A larger, expanded carapi stoixtewhal enlarged, showing more distinctlj the character of the 



surface ornamentation. 



Chemung group Warren, Wan-en. county, Pennsylvania. 

 Fig. 7. A nearly entire ma ,,,1". enlarged to two diameters, showing the arrangement of the 



sp^ules on the abdominal somites, and the very slender caudal spines. The anterior tion 



' f tin- carapace is somewhat restored in the drawing. 



Chemung group. Warren, \farren county, Pennsylvania. 

 Fig. 8. The righl valve of a Uirge carapace will, the abdomen attached. 



Chemung grqup. \\'<ir,ru, II ,,, ri ,,. , ownty, Pennsylvania. 

 Fig. 9. A fragment of shale preserving the remains of fifteen immature individuals, nine of which are 

 visible on the side represented in the figure. 



Chemung group. Warren, Warren county, Pennsylvania. 

 Id. An enlargement to three diameters of a portion of the postero-lateral surface of the right valve 

 showing the crenulated summit of the lower carina and the tuberculous character of the 

 upper carina. 



Chemung group. Warren, Warren county, Peiihsylvania. 

 Fig. 11. Two abdominal segment^, enlarged to two diameters, showing the bases of the spicules The 

 nodes across the middle of earl, segment ar spiniform when perfectly preserved. 



Chemung group. Warren, Warrei mty, Pennsylvania. 



Pig. 12. Three abd inal segme its and the post-abdomen of a large individual. 



Chemung group. Warren, Warn Pennsylvania. 



Mandibles of PnTLLOCARn>A. 



Page 170. 

 Fig. 13. A large specimen, natural size, showing the molar-like appearance of all the denticles except the 

 posterior one, which is sharp and composed of a single cusp. 

 Hamilton group. Pratt's Falls. Onondaga county. 

 Fig. 14. A specimen preserving the " manubrium " and showing the number and character of the cusps 



Hamilton group Pratt's Falls, Onondaga county. 

 Fig. If.. The crown ol a large example. 



Hamilton group. Pratt's Falls. Onondaga manly. 

 Fig. 16. A small example, showing but five cusps. In (his specimen the basal portion of the mandible is 

 not distinctly separated from the crown. 



Hamilton group. Pratt's Falls, Onondaga county. 

 Fig. 1 ,. A somewhat larger specimen, with a strong terminal cusp. 



Hamilton group. Pratt's Falls, Onondaga county. 



