NO. 1 BARNARD: AMPHIPODA OF THE FAMILY AMPELISCIDAE 29 



Remarks: There appear to be no intergrades in the material at hand 

 between the form of pleon segment 3 of typical Ampelisca cristata and 

 the new form. However, the specimens which I have separated from A. 

 cristata for the sake of convenience and given a new "subspecific" desig- 

 nation, show considerable variation in the above mentioned character. As 

 illustrated in the accompanying figures, it is seen that the tooth may 

 vary from the intermediate type seen in the holotype to the form in 

 figure G of plate 17, in which the angle of pleon segment 3 is nearly 

 quadrate. The most frequently occurring type is that similar to the 

 holotype and only the materials from Stations 1703-49 and 1925-49 have 

 the completely reduced form. 



Distribution: Along the coast of southern California and in the 

 Channel Islands, 6 to 52 fms ; along the coast of Lower California, 3 to 

 40 fms ; Guadelupe Island, 35 to 40 fms ; Gulf of California, 1 to 75 

 fms; Tenacatita Bay, Tangola Tangola Bay, and Isabel Island, Mexico, 

 2 to 25 fms; off San Jose Point, Guatemala, 7 to 20 fms; along the 

 coast of Costa Rica, shore to 48 fms; Bahia Honda and Secas Islands, 

 Panama, 12 to 20 fms; off Gorgona Island, Colombia, shore; off La 

 Plata Island, Ecuador, 45 to 55 fms. 



Ampelisca cristoides, new species 

 Plates 19 and 20 



Description of female: Head nearly as long as first 3 body segments, 

 anterior margin slightly incised, lower front margin parallel to upper 

 margin of head. Upper pair of eyes behind upper margin of antenna 1, 

 lower pair projecting from lower lateral angle of head. 



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

 1 of peduncle tumid; second article about half again as long as first, 

 third shorter than first. 



Antenna 2 about three fourths as long as body ; article 5 of peduncle 

 three fifths as long as 4. 



Mandible: spine row with 14 spines; article 3 of palp as long as 

 article 2. 



Maxilla 1 : outer plate armed with 1 1 spines ; article 2 of palp much 

 more slender than outer plate, apex with 4 spines, 3 cusp teeth, and 8 to 

 10 setae, and lined on outer edge with 4 long, simple setae. 



Maxilliped : inner plate reaching slightly beyond end of palp article 

 1, apex armed with 3 chisel teeth; outer plate reaching to end of palp 

 article 2, inner edge with 10 chisel teeth, rounded apex with 6 setal 

 spines, the outer 4 plumose. 



