CR USTA CEA—MALA COSTRA CA . 



377 



of large nodes bearing pustules, besides scattered pustules over the 

 rest of shell; abdominal somites increasing in length posteriorly 

 with two concentric rows of tubercles one posterior and one cen- 



FlG. 1679. Echinocaris socialis, X s- (After Beecher. ) 



tral; telson shorter than the lateral spines (cercopods), the latter 

 with a groove on the inside. 



Chemung of Warren, Pa., abundant. 



12. E. sublaevis Whitfield. (Fig. 1680, a, &.) Devonic. 



Length of hinge area about equal to height of carapace; poste- 

 rior end produced, rounded ; anterior end dorsal margins make a 



Fig. 1680. a, b, Echinocaris subicevis, left valve, and a few body and caudal seg- 

 ments ; c, E. pustulosa, right valve; d, E. multinodosa^ both valves in conjunction; 



/, y, Aristozoe canadensis, both valves. 



rectangle ; surface coarsely pustulose only at anterior end ; seg- 

 ments spinose. 



Chagrin (Erie) shales of Ohio. 



