376 BULLETIN OK THE BUREAU OF FISHERIES. 



d. Buccal frame roughly quadrate. 

 e. Last pair of legs modified in form and dorsal in position; openings of oviducts on coxopo- 



dites; first pleopods present in the female (Tribe Dromiacea). 



f. Eyes completely sheltered by orbits Family DROMnD.fi (p. 417). 



Jf. Eyes not sheltered by orbits. 



g. Legs of moderate length; gills 13 or 14 on each side Family Homoud^ (p. 419). 



gg. Legs excessively long and slender; gills 8 on each side. Family Latreii,lid.B (p. 419). 

 ee. Last pair of legs normal in form and position; openings of oviducts on the sternum; first 



pleopods wanting in the female (Tribe Brachygnatha). 



f. Body of medium width or broad in front; rostnun reduced or wanting; orbits well formed 



(Subtribe Brachyrhyncha). 



g. Free-living crabs with well-developed eyes and firm, hard carapace. 

 k. Carapace broad, short, rounded anteriorly. 



i. Distal articles of last pair of legs broad and thin, paddlelike 



Family Portunid/8 (p. 426). 



it. Distal articles of last pair of legs not paddlelike. 

 j. Anteimules folding longitudinally; outer maxillipeds long, overlapping the epi- 



stome Family Cancrid^ (p. 434). 



jj. Antennules folding transversely or obliquely transversely; outer maxillipeds 

 usually not overlapping the epistome. 



k. Body usually transversely oval Family XANTmD.^ (p. 43s). 



kk. Body usually square or squarish Family GoNOPLACiD/fi (p. 442). 



hh. Carapace more or less quadrilateral; frontal region curved downward. 

 i. Front broad, eyestalks of moderate length or short. . . .Family Grapsid^ (p. 447). 



n. Front of moderate width or narrow; eyestalks often very long 



Family Ocypodid^ (p. 450). 



gg. Small commensal crabs with very small eyes and orbits; carapace usually more or less 



membranous Family Pinnotherid^ (p. 442). 



ff. Body narrowed in front; rostrum usually distinct; orbits usually incomplete 



(Subtribe Oxyrhyncha). 



g. Chelipeds not a great deal larger than the other legs Family lNACHiD.a (p. 452). 



gg. Chelipeds much larger than any of the other legs Family PARTHENOPiD^fi (p. 461). 



dd. Buccal frame triangular, produced over the epistome (Tribe Oxysiomaia). 



e. First pair of legs chelate; body and legs normal; anteimse small. 

 /. Front of body not specially produced and upturned; eyes of normal size; maxillipeds 



more nearly horizontal Family Calappid^ (p. 420). 



Jf. Front of body produced into a projecting, upturned mass bearing the small eyes close 



together and closed in front by the more nearly vertical maxillipeds 



Family LEUCOSnD.^ (p. 423). 



ee. First pair of legs subchelate; body more or less abnormal in shape; last one or two pairs of 

 legs more dorsal than the others; antennae large Family Raninid^ (p. 420). 



Suborder NATANTIA. 



Decapod crustaceans of a shrimplike form having the abdomen strongly developed 

 and compressed, with its first segment little, if any, smaller than the others and with five 

 pairs of well-developed pleopods which are used for swimming. The cephalothorax is 

 usually also compressed and the legs are slender except that any one of the first three 

 pairs may be robust and chelate. Podobranchia are rarely present on the first three 

 pairs of legs and never on the last two pairs. The rostrum is usually strongly developed 

 and compressed. 



This important suborder, which comprises 185 genera, is divided into 3 tribes, of 

 which 2 are represented in the Beaufort fauna. 



