464 Wisconsin Academy cf Sciences, Arts, and Letters. 



line lamella, the endopodite is longer and is sometimes indis- 

 tinctly two-segmented. The left endopodite is very much 

 shorter in D. washingtonensis. 



DIAPTOMUS JUDAYI Sp. nOV. 



Plate XXII, fig. 6. Plate XXIII, figs. 1, 5. 



A small species. The first cephalothoracic segment is con- 

 siderably longer than the three following. The last segment 

 is armed with minute lateral spines. 



The first segment of the female abdomen is longer than the 

 rest of the abdomen. It is expanded laterally and in front 

 and bears two small lateral spines. On the posterior end of 

 the right side it bears a finger-like process projecting backward. 

 This process is somewhat shorter than in the other species of 

 the signicauda type. The second segment is about half the 

 length of the third. The furcal rami are rather less than 

 twice as lona- as their width, and are ciliate on the inner mar- 



gin. 



The antennae are 2 5 -segmented and extend a little beyond 

 the furcal rami. The right antenna of the male is much swollen 

 anterior to the geniculating joint, and bears a straight process 

 on the antepenultimate segment. This process is two-thirds 

 the length of the penultimate segTuent. 



The first basal segments of the female fifth feet are armed 

 with the customary spines. The second basal segments have 

 rather long lateral hairs. The exopodite is composed of two 

 segments, the third segment being represented by two spines. 

 The second segment is prolonged into the usual hook-like proc- 

 ess, and is denticulate on the inner margin. The endopodite 

 about equals in length the first segment of the exopodite, is 

 armed on the inner margin of the tip with hairs, and has two 

 rather long terminal spines. 



In the fifth feet of the male, the first basal segments are 

 armed with rather large spines. The second basal segment of 

 the right foot is trapezoidal in form and considerably longer 



