GAMMARIDEAN AMPHIPODA 65 



ventral coxal margin ; coxa 6 longer than broad, with long quadrate or 

 subquadrate posterior lobe ; hand of gnathopod 1 weakly tapering dis- 

 tally, article 5 much shorter than 6, posterior lobe narrow or of medium 

 width, dactyl fitting palm; article 5 of gnathopod 2 tumid, with 

 strongly and symmetrically rounded posterior margin; article 6 with 

 slightly chelate palm lacking extraordinary complex processes; distal 

 spine pair of article 6 on all pereopods of regular form, slightly sabre 

 shaped but not enlarged or highly modified; second articles of pereo- 

 pods 3-5 broadly expanded, posteroventral lobes weakly extended, 

 posterior margins minutely serrate; posteroventral corner of pleonal 

 epimeron 1 rounded, of epimeron 2 subrounded or very weakly sub- 

 quadate, of epimeron 3 w^eakly quadrate, angle obtuse, posterior edges 

 of epimera minutely serrate; pleonite 4 with long, rounded dorsal 

 hump ; uropods 1 and 2 with both rami spinose ; inner ramus of uropod 

 3 not exceeding base of article 2 of outer ramus ; telson cleft about two 

 thirds of its length. 



Distribution. — This species has been recorded from such widely 

 dispersed localities that it is presumed to live throughout the northern 

 cold-temperate and subarctic seas. The present record is the most 

 southerly yet published, except that made by Barnard (1964a) from 

 Laguna Beach, a few miles south of Santa Monica Bay. The speci- 

 men from Laguna Beach has a head and prebuccal structures more 

 similar to those of Woods Hole populations than do specimens from 

 the trap in Santa Monica Bay. 



The abundance of this species in the trap sample and its extreme 

 rarity in benthic grab samples suggests that the species in California 

 is epibenthic or demersal and thus escapes grab devices. Only the 

 one specimen from a depth of G4 meters at Laguna Beach was caught 

 in over 500 grab samples in depths of 10 to 183 meters. Hurley ( 1963) 

 did not find the species in the extensive Hancock collections of Califor- 

 nian benthos either; however, depths exceeding 200 meters have not 

 been adequately sampled, although J. L. Barnard (1966a) did not find 

 the species in several hundred samples from canyons and basins in 

 depths between 200 and 2000 meters. In summary, this species is now 

 recorded from southern California, in depths between 64 and 183 

 meters. 



Orchomene tabasco, new species 



Figures 27, 28 



Diagnosis. — Lateral cephalic lobes of medium wadth, subacute ; eyes 

 absent ; article 5 of antenna 2 shorter than article 4 ; epistome broadly 

 roimded anteriorly and projecting in front of upper lip; epistome 

 flatter in juvenile than in adult; palp article 1 of mandible shorter 

 than article 3; some spines of outer plate of maxilla 1 disjunct; coxa 1 



