194 University of California Publications in Zoology [Vol. 23 



B. Basal joint of antennae usually either extensively produced outward 

 or with one or more distal spines. Eyes with orbits. Postocular 

 spine cupped, or with dense growth of hair on anterior face so that 

 cornea of retracted eye is partially concealed from above. Exogn,ath 

 of outer maxillipeds widest in basal half, tapering gradually. Bos- 

 trum bifid. 



1. No preocular spine. 



a. Carapace but slightly longer than wide; surface uneven, tubercu- 



lated or spiny. Eostrum short, flattened, and notched. 



Chionoecetes, p. 209. 



b. Carapace much longer than wide; surface smooth, devoid of 



spines. Eostrum composed of two narrow, divergent spines, 

 united basally, for half their length. (Not known north of 

 San Pedro.) 



Telia, p. 210. 



2. A preocular spine. 



a. Postocular spine flattened and densely hairy on anterior face. 



Carapace with numerous or very prominent tubercles or spines. 

 Eostrum bifid. (Not known north of Point Eeyes.) 



Loxorhynchus, p. 212. 



b. Postocular spine deeply cupped on anterior face and without 



hairs, 

 i. Eostrum composed of two long, slender, straight, cylindrical 

 spines, diverging from the base. Carapace pyriform, in- 

 flated, and covered with sharp spines of unequal length. 



Chorilia, p. 208. 

 ii. Eostrum composed of two short, flattened horns. 



a. Eostral horns extremely flattened and leaf -like, about one- 



quarter length of carapace. Orbits deep. Outer mar- 

 gin of basal antennal joint flattened and produced, not 

 spiny. Carapace subpyriform, furnished with rounded 

 tubercles. 



Scyra, p. 213. 



b. Eostral horns very short, one-ninth to one-tenth length of 



carapace. Orbits shallow. Outer margin of basal 

 antennal joint not produced, spiny. Carapace sub- 

 orbicular, tuberculated. (Not known north of Mon- 

 terey Bay.) 



Rerbstia, p. 215. 



As can be seen from a review of the above key, the genera of the Inachidae 



arrange themselves into two major groups, based on the proportions of the basal 



antennal joints. In order to facilitate the presentation of generic definitions, 



they are so grouped below: 



I. Basal joint of antennae extremely slender throughout its length and usually 

 long; length measured from raised margin of endostome to insertion of 

 free joints greater than or at least equal to the combined width of the 

 joints and tliat portion of the epistome or awtennular fossettes lying be- 

 tween them, measured from bases of eye-stalks {middle of lower orbital 

 margin). (Group II, p. 200.) 



