S. I. jSi/ilth—Aitip/tt'po<lHS(/e/iera, etc. 269 



of the ])era'on taken together, :ui(l in tlie male about a fourth as k>ng 

 as the entire pera^on, hut shorter in tlie feinak' on account of the 

 elongation of the middle segments of the peneon in that sex. There 

 is a slight dorsal carina on the anterior part of the head, and the 

 anterior margin projects in a slight rostrum in the middle, and at the 

 sides in slightly prominent lohes in which the small black eyes are 

 situated. In the lateral margin below the eye there is a large 

 emargination over the base of the antenna as in the allied genera. 

 In the male the seven segments of the per^eon are about equal in 

 length, but in the female the first and last are shorter and the fourth 

 and fifth longer than any of the others, the fourth and fifth being 

 each about twice as long as either the first or last. The epimera are 

 all long and low : those of the first four segments are small and 

 inconspicuous; the fifth (Plate Ila, figure 4, a) is much larger and 

 projects in a conspicuous, broad and rounded lobe in front of the 

 articulation of the limb ; the sixth and seventh are similar in form 

 but successively much smaller. 



In the male, the antennulse and antennas are approximately equal 

 in length. The antennuhie are slightly more than half as long as the 

 rest of the animal : the first segment of the peduncle is very stout, 

 but compressed laterally and the lower edge raised into a carina 

 which is prominent near the base, where the dorso-ventral diameter 

 is more than half the length of the segment ; the second and third 

 segments are sub-equal in length and diameter and each is slightly 

 longer than the first ; the flagellum is about as long as the third 

 segment of the peduncle and is composed of three segments, of which 

 the first is rather longer than the second and third taken together. 

 All the segments are furnished with long setiform hairs below and 

 with much fewer and shorter ones above. The antennae are a very 

 little shorter than the antennulae and scarcely, if at all, stouter; the 

 third segment of the peduncle is no longer than broad ; the fourth 

 is about as long as the second of the antennula ; the fifth is a little 

 longer than the foui-th ; the flagellum is scarcely as long as the fifth 

 segment of the peduncle and is composed of three segments, of 

 which the first is considerably longer than the second and third 

 together. All the segments beyond the third are furnished with 

 setiform hairs very much as in the antennulge. In the female, the 

 antennulae and antennae are proportionally more than a fourth shorter 

 than in the male, the diflerence resulting mostly from the shortening 

 of the flagella and the distal segments of the peduncles. 



The mandibles are nearly as in the Ericthonius diffonnis. The 



