PART 1 GARTH : PACIFIC OXYRHYNCHA 79 



Diagnosis: Rostrum small, tip bifid. Carapace hairy but non- 

 granulate ; two median spines, one gastric, one cardiac. Postorbital tooth 

 broad at base, anterior margin concave. Basal antennal article with 

 inner margin produced as a thin blade. Legs stout, smooth, margins hairy. 



Description: Carapace subpyriform, convex, regions separated by 

 pilose depressions, nongranulate, but with minute punctae forming 

 linear striations on branchial and intestinal portions. Rostrum small, 

 horizontal, sides converging gradually to bidentate tip, teeth minutely 

 denticulate, intervening sinus U-shaped, a granular swelling at base 

 between anterior margins of orbit. Postorbital tooth broad at base, 

 anterior margin proximally convex, then sharply concave opposite cornea 

 of eye, tooth set off from base of eyestalk by a deep and narrow fissure. 

 Gastric and cardiac areas smooth and glabrous, each surmounted by an 

 erect spine, that of cardiac region longer by one third, a horizontal row 

 of hairs across anterior gastric region. Hepatic regions small, crowded 

 forward and downward by large branchial regions, one or two granules 

 at apex of each. Branchial regions, though swollen, not protruding 

 beyond general outline of carapace and set off from genital area by deeply 

 pitted grooves. Inner metabranchial areas sculptured with a fine-lined 

 pattern of pits and grooves. Intestinal region not produced posteriorly, 

 bearing two minute granules side by side. A raised, thickened postero- 

 lateral marginal ridge. 



Basal antennal article smooth, produced inwardly and downwardly 

 as a flange with an entire margin culminating in an anterior tooth ex- 

 tending forward nearly as far as the tip of the rostrum, external margin 

 also culminating in a tooth, a few granules at midpoint opposite base of 

 eyestalks. Antennal flagella long, between one-third and one-half carapace 

 length. Merus of external maxilliped cordiform, deeply notched to re- 

 ceive three-segmented palp, which is coarse and hairy. A double row of 

 granules on each pterygostomian region. 



Cheliped of female feeble, hand slender, fingers meeting without 

 gape. Walking legs exceptionally robust, dorsal surfaces smooth and 

 porcellanous, anterior and posterior margins fringed with long, silken 

 hairs. Dactyli equaling or exceeding propodi in length, curving but 

 slightly except at extreme tips. 



Female abdomen without a spine but with a suggestion of a low 

 tubercle on first segment, middle portion of second and each succeeding 

 segment raised, only this center portion retaining indications of 

 metameres in the fused terminal portion, comprising somites 5-7. 



