NO. 1 BARNARD : AMPHIPODA OF THE FAMILY AMPELISCIDAE 43 



several problems concerning this species. The materials at hand differ 

 from the figures of this species in Sars (1895) by the longer article 7 

 of peraeopods 1 and 2. Holmes (1905) has noticed a variability in this 

 feature, but it appears to be rather constant in the present specimens. 



Distribution: Widely distributed in the Channel Islands and along 

 the coast of southern California, 16 to 115 fms; off 10 Mile Creek, 

 south of Winchester Bay, Oregon, 20 to 40 fms; northeast of Middle 

 Farallon Island, 37 fms; 4 miles north of Todos Santos Island, Lower 

 California, 41 fms. 



Ampelisca indentata, new species 

 Plate 30 



Descriptor, of female: Head about as long as first 2 body segments, 

 front margin slightly concave, lower front margin deeply incised and 

 containing lower pair of eyes. Upper pair of eyes behind upper edge of 

 antenna 1. 



Antenna 1 reaching end of peduncle of antenna 2; article 1 of pe- 

 duncle almost as long as article 2, article 3 about half as long as 1. 



Antenna 2 nearly as long as body or somewhat shorter; article 5 

 of peduncle four fifths as long as 4. 



Mandible: spine row with 8 spines; article 3 of palp two thirds as 

 long as article 2 ; the latter article rather stout. 



Maxilla 1 : outer plate with 9 to 10 spines; palp article 2 narrower 

 than outer plate, apex armed with 4 spines and 3 cusp teeth. 



Maxilliped: inner plate rather slender, reaching to end of palp ar- 

 ticle 1, apex with a single chisel tooth; outer plate reaching to end of 

 palp article 2, inner edge lined with 7 chisel teeth, rounded apex with 

 5 setal spines, the outer 2 plumose. 



Coxae 1 and 2: lower posterior angle slit; coxa 3 without slit. 



Gnathopod 1 : article 6 about as long as 5, posterior edge strongly 

 inflated and armed with spines and setae ; article 7 short, stout. 



Gnathopod 2: article 6 about half as long as 5, article 7 about half 

 as long as 5. 



Peraeopod 1 similar to that of Ampelisca pugetica Stimpson. 



Peraeopod 2 : articles 2 and 4 very turgid, article 4 about as long as 

 in peraeopod 1. 



Peraeopod 3: posterior edge of article 5 with 3 sets of spines, pos- 

 terior edge of article 6 with 1 spine. 



Peraeopod 4 similar to 3 but with generic differences. 



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