158 CRUSTACEA. 



FAMILY I. CORYSTID.E. 



Gorystes (Leach). Carapace much longer than 

 wide, ovate, cut with few teeth at the sides ; outer 

 antennae together forming a tube. 



C. Cassivelaunus. Fig. 298 ; J- n. s. 



Atelecyclus (Leach). Carapace nearly circular, 

 evenly convex, cut with many teeth. 

 A. heterodon. Fig. 299 ; i n. s. 



298 



299 



301 



303 



Thia (Leach). Carapace heart-shaped, narrowed 

 behind, arched from side to side only ; front forming 

 a broad plate concealing the eyes. 

 T. polita. Fig. 300 ; n. s. 



