4S2 



]\Ir. L. A. Borradaile on the 



ii. First antennae fold slanting or 



transversely. 



(rt) Jiody usually transversely oval. 



Male openings rarely sternal. 



Not sharply separated from the 



following family Xanthidae. 



(i) Body usually square or squarish. 

 Male ducts open on the sternum, 

 or, if coxal, pass along a groove 

 in the stex'num. Not sharply 

 separated from the foregoing 

 family Gonoplacidae. 



B. Carpopodites of third maxillipeds do not 



articulate at or near the inner angle of the 

 meropodites. Body usually square or 

 squarish. Male openings sternal, except 

 in Ptenoplax, where the duct passes along 

 a sternal groove to the coxopodite. In no 

 species is the right chela always larger 

 than the left. 



1. Small symbiotic crabs, with very small 



eyes and orbits. Body usually more or 



less rounded Pinnotheridae. 



2. Free-living crabs, with eyes not specially 



reduced and usually a square body. 



a. Last pair of legs dorsally placed and 



weaker than the others. Interan- 



tennular septum very thin. [No 



distinct epistome. Exopodites of 



third maxillipeds not hidden.] 

 i. Front narrow. Female opening in 

 normal position. Third maxilli- 

 peds subpediform, not covering the 



mouth Ptenoplacidae. 



ii. Front moderately broad. Female 

 openings on the sternal segment 

 con-esponding to first pair of walk- 

 ing-legs. Third maxillipeds cover 

 the mouth ventrally and have very 

 small meropodites Palicidae. 



b. Last pair of legs not dorsally placed 



nor markedly weaker than the rest. 

 Interantennular septum not very 

 thin, except in Macrophthalminse. 

 i. A gap of greater or less size is left 

 between "the third maxillipeds. 

 Front broad or moderately so. 

 (a) Sides of the body either straight 

 or very slightly arched. Shape 

 square. Rarely true land-crabs. Grapsidae. 

 (5) Sides ofthe body arched. Shape 



transversely oval. Land-crabs . Gecarcinidae. 

 ii. Third maxillipeds almost or quite 

 close the mouth. Front mode- 

 rately or very narrow Ocypodidae. 



C. Meropodite in third maxillipeds small, 



bearing terminally a carpopodite of 



