454 Wisconsin Academy of Sciences, Arts, and Letters. 



DIAPTOMUS T.INTONI ForbcS. 



Plate XXVII, figs. 4, 5, 7. 



1893. Diaptomus Lintoni Forbes, p. 252 ; pi. XLII, figs. 26- 



28. 

 1895. Diaptomus Lintoni Herrick and Turner, p. 68 ; pi. V, 



fio- 12 

 1897. Diaptomus Lintoiii Schacht, p. 127 ; pi XXVII, fig. 1. 



"A large red species occurring commonly with D. sJiosJione; 

 but distinguishable from it at a glance by its different shape, 

 its longer antennae, its smaller size, and by characters derived 

 from the right antenna and the fifth foot of the male. The 

 thorax is symmetrically elliptical in shape, broadest at the 

 middle. The posterior angles are not produced or bifid, but 

 are each armed with a minute spine. The first segment of the 

 abdomen of the female is not especially produced, but bears at 

 its broadest part a minute spine on each side. The abdouien 

 itself is very short, its length contained about three and one- 

 third tiuies in that of the cephalothorax. The antenna of the 

 female is long and slender, 25-jointed, reaching a little beyond 

 the tip of the abdomen. 



"The fifth pair of legs in this sex is similar to tliose of D. 

 shoslione, but much smaller. The inner ramus is not jointed. 

 It is longer than the basal joint of the outer ramus, bears two 

 stout plumose setae at its tip, somewhat shorter than the ramus 

 itself, and has likewise at its inner tip a patch of small spines 

 or fine hairs. The second segment of the outer ramus with 

 its terminal claw is two-thirds as long again as the preceding 

 segment, the breadth of the latter two-thirds its length. The 

 third joint is indicated by a single long, stout seta and one or 

 two smaller ones. 



"In the male the geniculate antenna is relatively rather slen- 

 der, its last two joints without special appendages, its penulti- 

 mate with a slender transparent apical process, reaching about 

 to the middle of the succeeding segment, acute at tip, but 

 neither serrate nor emarffiuate. 



