478 Mr. L. A. Borradaile on the 



Key to the Families of the Oxystomata. 



I. Body of the shape usual in crabs. Abdomen 



hidden under thorax. Antennae small. 

 Legs normal in position. 



A. Afferent openings to gill-chambers lie in 



front of first legs (chelipeds). Gills 9 on 



each side. Male openings coxa) ....... . Calappidae. 



B. Afferent openings to gill-chambers lie on 



either side of the mouth at the base of the 

 third maxillipeds. Gills less than 9 a side. 

 Male openings sternal Leucosiidae. 



II. Body more or less abnormal in shape. Ab- 



domen not hidden under thorax. Antennae 

 large. Last one or two pairs of legs in a 

 more dorsal position than the rest. 



A. Carapace .'short. Last two pairs of legs 



subprehensile, with hooli-lilie end-joints . . Dorippidae. 



B. Carapace long. Legs usually have the last 



two joints very broad Raninidae. 



Key to the Subfamilies of the Calappidae. 



I. Last three joints in third maxillipeds not 



hidden by the meropodite. Orbits not sepa- 

 rated from the antennular sockets. 



A. Meropodites of third maxillipeds not elon- 



gate nor acute. Exopodites of same limbs 

 with flagella. Legs not adapted for 

 swimming Caluppinee. 



B. Meropodites of third maxillipeds elongate 



and acute. Exopodites of same limbs 

 without flagella. Legs adapted for 

 swimming Orithyince, 



II. Last three joints in third maxillipeds hidden 



by the meropodite. Orbits more or less 

 .separated from the antennular sockets. 

 [Exopodites of third maxillipeds with fla- 

 gella. Meropodite in same limbs elongate 

 and acute. Legs may be adapted for swim- 

 ming or not.] MatutincE. 



Key to the Subfamilies of the Leucosiidae. 



I. Meropodites of third maxillipeds more than 

 half the leng-th of the ischiopodites. Fingers 

 stout, gradually narrowing from base to tip, 



usually shorter than the palm LeucosiineB, 



II. Meropodites of third maxillipeds never more 

 than half the length of the ischiopodites. 

 Fingers slender, of even width from the base 

 to near the tip, usually longer than palm . . Iliince. 



Key to the Subfamilies of the Dorippidas. 



I. Third maxillipeds leave a good part of the 

 mouth uncovered. Inward openings to the 

 gills near the base of the chelipeds Dorippince. 



