34 (33) Body conspicuously narrowed in front; rostrum usually distinct and often forked; or- 

 bits often incomplete Superfamily Oxyrhyncha, spider crabs 



.35 



34 {33) Body moderate to broad in front; rostrum absent or greatly reduced; orbits usually 



complete Superfamily Brachyrhyncha 



41 



35 (34) Chelipeds not much larger than other legs Family Majidae 36 



35 (34) Chelipeds very much larger than other legs Family Parthenopidae 40 



36 (35) Whole length of rostral horns either coalesced or closely approximated along mid- 

 line; male abdomen terminally broadened, telson elliptical to subquadrate 



Subfamily Oregoniinae, Hyas 



A (36) Hepatic region behind post- 

 orbital spine not expanded 



H. araneus 



Figure 68. — Hyas araneus: A, carapace and eyes; 



B, male abdomen. 



A (36) Hepatic region behind postorbital spine 



expanded laterally H. coarctatus 



Figure 69. — Hyas coarctatus, carapace and eyes. 



36 (35) Rostral horns divergent near tip; male abdomen not terminally 

 broadened, telson subtriangular 



Figure 70. — Male abdomen of spider crab 

 with subtriangular telson. 



25 



