222 STALK-EYED CRUSTACEA 



a. Carapace more than one and a half times as wide 

 as long, including spines. — (P. nicaraguensis^ 



b. Carapace less than one and a half times as wide as 

 long, including spines. — {P. annatiis.) 



I. Potamocarcinus latifrons. 



Potamocarci)iHS latifrons . . . Randall, Rathbun. 

 Potaniocarcimis scJioinburgkil ., White. 



The carapace is flat, with the teeth of antero-lateral 

 edge sometimes bifid. The external appendage of the 

 external maxillipedes is very short, being less than one- 

 third the length of the third joint. Colour brown. 



Range. — British Guiana, Cayenne. 



2. Potamocarcinus nicaraguensis. 



Potamocarcinus nicaraguensis . . . Rathbun. 



The carapace is more than one and a half times as 

 wide as long, including lateral spines, which are of same 

 size, with some bifid. The length of the external 

 appendage of the external maxillipedes is more than 

 one-third the length of the third joint. 



Range. — Nicaragua, Costa Rica. 



3. Potamocarcinus armatus. 



Pota)nocarcinus armatus . Milne Edwards, Rathbun. 



The carapace is less than one and a half times as wide 

 as long, including lateral spines. The length of the 

 external appendage of the external maxillipedes is more 

 than one-third the length of the second joint. 



Range. — Not known. 



