ILaguna S^arine ILaboratorp 149 



Hyalella azteca (Sauss) 

 (Figure 84) 



Body smooth, slightly compressed. Pleon segments one and two 

 each produced into a small dorsal tooth. Side-plates one to four 

 somewhat rectangular. Eyes nearly round. Antenna one, five to 

 eight-jointed, flagellum longer than peduncle ; joints of peduncle suc- 

 cessively diminishing in length. Antenna two, slightly longer, the 

 seven to ten-jointed flagellum longer than peduncle; joints of 

 peduncle successively increasing in length. Maxillipeds, inner plate 

 tipped with three short, stout spines, and edged on the inner side 

 with slender compound setae; outer plate with nine toothed spines 

 and very small palp. Maxilla two, both plates apically fringed with 

 fine spinules, which, on the inner plate, are edged with two plumose 

 setae. Mandible normal, principal and secondary plates dentate, 

 plumose spinules in spine-row, molar large, with compound seta. 



Gnathopod one, small, slender, fourth joint with small pellucid 

 boss on the distal hind end ; fifth joint with bulging hind margin, 

 fringed with row of spines and short teeth; sixth joint not so wide, 

 but sub-equal in length, hind margin covered with fine, short hairs, 

 curved finger reaching to end of the transverse, toothed palm. 

 Gnathopod two in both male and female, with bulging fifth joint 

 edged with spines, sixth joint in male very large and stout, longer 

 than broad, oblique palm with two notches underneath the strong, 

 curved finger. Finger not reaching to hinder margin of palm, but 

 closing between two spines just in front of a third notch. Gnath- 

 opod two in female, longer and stronger than gnathopod one, fifth 

 joint considerably produced behind, sixth joint twice as long as 

 widest part ; hind part produced somewhat beyond the small curved 

 finger and the convex, transverse palm. Perseopods three to five, 

 second joint broadly expanded, serrate; peraeopods four and five 

 nearly equal in length. Pleopods plumose. Uropod three, ramus 

 slender, tipped with setae, and subequal to peduncle. Telson, broad 

 as long; rounded apical margin with slender seta on either side of 

 tip. 



Specimens agreeing well with description of H. azteca in Da a 

 Tierreich, except in being smaller, and in having, commonly, fewer 

 joints in the antennae. They differ from the family description of 

 Talitridae in having the inner plate of maxilla one tipped with three 

 plumose setae, and in having the fine spinules of the inner plate of 

 maxilla two edged with two plumose setae. 



Color varying from light bluish green to light green and brown. 



Frequent in fresh water pond about five miles inland from 

 Laguna Beach, California. Coll. H. V. M. Hall. 



