2i6 STALK-EYED CRUSTACEA 



suture absent or faintly indicated. The fourth joint 

 of the external maxillipedes has its outer margin 

 convex, forming a single curve to the insertion of the 

 fifth joint. Exognath reduced to a stump. Cervical 

 sutures curved, arching towards each other. 

 Brazil. 



20. Pseudothelphusa dilatata, 



Superior margin of the front not keeled, tuberculate, 

 with lower margin convex. Cervical suture sinuous. The 

 fourth joint of the external maxillipedes has its outer 

 margin convex, forming a single curve to the insertion 

 of the fifth joint. The external appendage (exognath) 

 is not reduced to a stump, being about half the length 

 of the third joint. 



Mexico. 



21. Pseudothelphusa sulcifrons. 



Superior margin of the front not keeled, tuberculate, 

 with lower margin convex. Cervical suture nearly 

 straight. The fourth joint of the external maxillipedes 

 has its outer margin convex, forming a single curve to 

 the insertion of the fifth joint. Exognath is about half 

 the length of the third joint. 



Mexico. 



22. Pseudothelphusa bisuturalis. 



Carapace smooth to the naked eye. Superior margin 

 of front not keeled, tuberculate, with the inferior margin 

 sinuous or straight. The fourth joint of the external 

 maxillipedes has its outer margin convex, forming a 



