12 BULLETIN 129^ UNITED STATES NATIONAL MUSEUM 



C. Postorbital tooth large, close to the orbit and curving about the ex- 

 tremity of the eye, so that its outer margin is subparallel to the 

 median line. 

 D'. Carapace broadly ovate, with very short rostrum. Chelipeds not 

 longer than carapace. Second and third pairs of legs longest. 



Dasygyius, p. 137. 



D^. Carapace triangular-ovate, with long, pointed rostrum. Chelipeds 



longer than carapace. Ambulatory legs diminishing successively 



in length from first to fourth pair Pyromaia, p. 127. 



C^. Postorbital tooth either small, or, if large, not curving around end of eye. 

 D^ Rostrum longer than its basal width or, exceptionally, just as long. 

 E^ Rostrum divided into two narrow spines. 



F^ Ambulatory legs of moderate length, not prehensile. 



Oregonia, p. 70. 

 F^. Ambulatory legs long, prehensile, the propodites more or less 



dilated and compressed Eurypodius, p. 80. 



E^. Rostrum simple, spiniform, or terminating in a spine. 



F'. Sexes differing markedly in shape of carapace, postorbital spine 

 and cheliped. Chelipeds of male extremely long, several 

 times as long as postrostral portion of carapace. 



Erileptus, p. 68. 



F^. Sexes differing only in the usual way. Cnelipeds of male not 



noticeably long. 



G'. Legs subprehensile, the propodites more or less enlarged dis- 



tally, the dactyli curved. Carapace sparingly granulate or 



smooth except for a few tubercles Inachoides, p. 59. 



G^. Legs not subprehensile, the last two articles slender. Cara- 

 pace very rough between the spines and tubercles. 



Anasimus, p. 64. 

 D^. Rostrum shorter, or no longer, than its basal width. 



E'. Eyestalks slender, extending laterally beyond the oblong, post- 

 orbital lobes. Ambulatory legs long, filiform. Three erect, 



median, dorsal spines Arachnopsis, p. 89. 



E^. Eyestalks not slender. 



F^ Seven long, capitate, dorsal spines. Anterior margin of hepatic 

 region oblique to median line. Basal antennal article and 



male sternum sharply cristate Aepinus, p. 92. 



F^. Dorsal surface when spinous, not furnished with seven long 

 capitate spines. 

 G'. Carapace depressed, the branchial regions considerably flat- 

 tened posteriorly and laterally, so that their lateral margins 

 are visible from above for nearly their whole length. 

 H'. First and second ambulatory legs of about equal length and 

 longer than third and fourth legs. Fostocular process 

 usually large. Hepatic region with outer margin con- 

 vex CoUodes, p. 105. 



H^. First ambulatory leg much longer than the other legs in 

 male; legs all short in female. Postocular process typi- 

 cally small. Hepatic region with angular outline, its 

 anterior margin at right angles to median line and approxi- 

 mating the postorbital process Batrachonotus, p. 122. 



G^. Carapace higher and more convex, the branchial regions not 

 remarkably flattened, their lateral margins for the most 

 part invisible in dorsal view. Ambulatory legs of first 

 pair much the longest. Rostrum bilobed. 



Euprognatha, p. 95. 



