254 Illinois State Laboratory of Natural History. 



the distal part of the inner margin with long delicate hairs. 

 This segment is much simpler than the corresponding seg- 

 ment of lacustris and nevadensis. 



Fifth pair of legs of the female imiramose, three-segmented. 

 First segment subquadrate, somewhat longer than wide, 

 armed near the outer distal angle with a hair or delicate 

 spine. Second segment somewhat narrower than the first 

 and slightly longer ; armed at the outer apical angle with a 

 small sharp spine. Third segment slightly narrower than 

 the second and barely one and a half times as long ; armed 

 with five or six spines*, two (one) outer, one inner, and three 

 apical. Of the outer spines, the upper one is at about the mid- 

 dle of the segment and the lower one is directly opposite the 

 inner spine. Of the apical spines, the middle one is spinu- 

 lose on both margins and the outer one on the inner margin. + 



Length of female 1.9 mm. ;t that of male 1.1 mm. 



The above description was prepared from specimens kindly 

 sent me by Dr. Lillejeborg, the measurements, however, with 

 the modification explained in the foot-note, being those given 

 in the original description. The material was a part of that 

 collected by Dr. C Xystrom, a member of the Xordenskiold 

 expedition to Greenland in 1871, and was not in the best 

 state of preservation, owing no doubt to the length of time 

 since its collection. 



Figures of this species may be found in de Guerne and 

 Richard's "Revision" ('89b), and imperfect copies of these 

 in Herrick's "Synopsis" (Herrick and Turner '95). The 

 fifth pair of legs of the male are correctly represented in the 

 "lievision" except that the spine at the outer apical angle of 

 the right leg is not shown ; indeed it is not mentioned in the 

 description. The spine figured on the outer margin of the 



* The armature of this --eminent differs somewhat in different specimens. See on 

 a subsequent page the discussion in regard to the fifth leg of the female. 



t Having only a few specimens to study. I could not satisfactorily determine 

 whether the other spines were also spinulose or not. but I am quite positive with re- 

 gard to the two mentioned. I think it likely that they are armed as in lacustris. 



i It is quite evident that a mistake was made in regard to the measurements given 

 in the original description: " Length of female, caudal seta' excepted, about 3.9 mm., 

 and of male 1.1 mm." In the specimens I examined there was no such difference in 

 length in favor of the female; in fact the single entire female I had the opportunity 

 to measure was 1.333 mm. in length, while the average length of five males was con- 

 siderably above this— 1.698 mm. I have hesitated to substitute these measurements 

 because of the limited number examined, and have altered Lillejeborg's figures to 

 what I think they were intended to he. 



