NO. 1 BARNARD : AMPHIPODA OF THE FAMILY AMPELISCIDAE 45 



It bears some resemblance to A. senegalensis Chevreux (1925), but 

 is distinguishable by the shape of the head, the rami of uropod 3, and 

 the length of uropod 1. 



Distribution : Channel Islands and along the coast of southern Cali- 

 fornia, 15 to 55 fms; Gulf of California, off San Gabriel Bay, Espiritu 

 Santo Island, 21 fms. 



Ampelisca mexicana, new species 

 Plates 31 and 32 



Description of female: Head not as long as first 3 body segments, 

 anterior edge slightly incised, lower front edge oblique, margin nearly 

 straight. Upper pair of eyes behind upper edge of antenna 1, lower pair 

 at lateral angle of head. 



Antenna 1 reaching nearly to end of peduncle of antenna 2 ; article 2 

 of peduncle longer than 1 ; article 1 rather slender ; article 3 shorter 

 than 1. 



Antenna 2: flagellum broken; article 5 of peduncle about three 

 fourths as long as article 4. 



Mandible: spine row with 7 spines; article 3 of palp as long as 

 article 2. 



Maxilla 1 : inner plate slender, conical, apex with 2 setae ; outer 

 plate with 9 spines ; apex of palp with 4 spines, 3 cusp teeth and 6 setae. 



Maxilliped: inner plate reaching to end of palp article 1, apex with 

 a single large chisel tooth ; outer plate reaching to end of palp article 2, 

 inner margin lined with 8 chisel teeth, rounded apex with 3 setal spines, 

 the outermost one plumose. Palp normal. 



Coxal plates 1 and 2 : lower posterior angle with a small slit. Coxal 

 plate 3 without slit. 



Gnathopod 1 : article 5 longer than article 6 ; posterior edge of ar- 

 ticle 6 strongly inflated and heavily armed with spines and setae; ar- 

 ticle 7 moderately strong. 



Gnathopod 2 very slender; article 6 slightly more than half as long 

 as article 5 ; article 7 two thirds as long as 6. 



Peraeopod 1 : article 7 about as long as articles 5 and 6 combined ; 

 distal anterior edge of article 4 not produced. 



Peraeopod 2 similar to 1 but with generic differences. 



Peraeopod 3 : anterior edge of article 2 setose ; posterior edge of ar- 

 ticle 5 with 2 sets of spines (1 each) ; posterior edge of article 6 with 

 1 spine. 



Peraeopod 4 similar to 3 but with generic differences. 



