202 STALK-EYED CRUSTACEA 



/;. The fifth joint of the external maxiHipedcs is 

 inserted at the external angle of the fourth, or is hid 

 behind it. The carapace is oval. — {Geocat'cinidcB.) 



c. The fifth joint of the external maxillipedes is 

 inserted at the summit or at the external angle of the 

 fourth joint. The carapace is circular or triangulate. — 

 {Phinot/ierid(Z.) 



d. Carapace quadrilateral or rhomboidal ; anterior and 

 lateral borders almost straight or slightly curved. 



d^. The second joint of the male abdomen does not 

 hide the sternum below it. Eye-stalks almost always 

 very long. — (Ocypodid's) 



e^. The second joint of the male abdomen almost always 

 hides the sternum below it. Eye-stalks very short. — 

 (G raps idee.) 



Family I. Thelphusidae. 



TJielpJinsidir . . Dana, Miers. 

 Thelplieusiens . . H. Milne Edwards. 

 Potauwnida' . . Ortmann, Rathbun. 



The carapace, transverse, rounded, or more or less 

 quadrilateral, is slightly or not at all convex, or may be 

 convex antero-posteriorly ; its anterior border is straight, 

 and occupies about two-thirds of its transverse diameter, 

 or may be almost as broad as the carapace ; the lateral 

 borders may form a regular curve, or may be more or less 

 straight, and armed with teeth that are of some size or are 

 microscopic. The front, wider than the anterior portion 

 of the buccal cavity, may be or may not be bent down- 

 wards ; if the latter, the bend may be a gradual slope, or 

 a sudden bend, the bending being indicated by a ridge 

 (the superior frontal border) which may be more advanced 

 than the lower free border. The eyes have a large and 



