North American Centropagidce. 259 



nevadensis Columbia Forbes; on other specimens collected in 

 the same localities — Swan Lake and Flathead Lake, Montana ; 

 and on specimens from Gamble's Lake and Lake Pend 

 d'Oreille, Idaho, from Lake Tahkemitch and Tsiltcoos Lake, 

 Oregon, and from Lake Union and Lake Washington, Wash- 

 ington, sent to the State Laboratory by Messrs. Evermann 

 and Meek of the U. S. Fish Commission. I had also a large 

 number of the Nevada form kindly sent me by Prof. Lillje- 

 borg, but, unfortunately, there was not a single mature indi- 

 vidual in this lot, and for this reason I cannot say on my own 

 responsibility that E. nevadensis Lilljeborg and E. nevaden- 

 sis Columbia Forbes are identical. A careful examination of 

 the material at hand, however, inclined me to that belief, and, 

 moreover, Professor Schmeil, both in a personal letter and 

 later in the "Bibliotheka Zoologica " (Schmeil, '97) says that 

 they are, after having examined authentic specimens from 

 both localities. He states also that Professor Forbes was 

 perfectly justified in establishing his Columbia, as a new 

 variety, since Lilljeborg's descriptions and figures are inac- 

 curate in several respects. In the following paragraph are 

 given the points in which my observations differ from those 

 of Forbes and of Lilljeborg. 



In all the specimens examined the segments of the fifth leg 

 of the female are proportionately longer and narrower than 

 figured by Lilljeborg. This fact may be due to his having 

 .made his drawings from an individual not perfectly matured. 

 This difference was noted by Forbes in his description of 

 Columbia ('93). The appendage near the outer distal angle 

 of the first segment of this leg is correctly drawn as a seta by 

 Lilljeborg, while Forbes's figure represents it as spine-like. 

 The fact that a second spine is occasionally found at the outer 

 distal angle of the second segment must have been observed 

 by Lilljeborg, since his drawings show it, although no mention 

 of it is made in the original description of nevadensis (de 

 Guerne et Richard, '89b). Forbes refers to it in his descrip- 

 tion of Columbia? but does not figure it. A seventh spine on 

 the outer margin of the last segment was correctly said by 

 Forbes to be occasionally present. Lilljeborg does not seem 



