COLLEMBOLA OF MINNESOTA 79 



The description is taken entire from Brook's "Revision 

 of the genus Entomobrya." The species is regarded as quite 

 variable, and according to the author quoted, exhibits several 

 varieties which have been described as different species. While 

 many of my specimens answer well to the above description, 

 many others do not, and indeed it is the most perplexing spe- 

 cies I know of. Our most common form seems to me rather 

 larger, proportionately narrower, and with less distinct mark- 

 ings than the type. Not unlikely it is more than a variety, 

 yet the color gradations are so perfect in a large series that it 

 seems safer for the present to leave it as it is. A few very pale 

 specimens have been taken which show scarcely any color on 

 the body. 



Tomocerus arcticus Schott. 



PL VI, Figs. 1-9; Vn, Figs. i-4b. 



1893. Tomocerus arcticus. Schott, Palsearct. Coll. p. 43. PI. Ill, 89. 

 1896. Tomocerus arcticus. Schaffer, Coll. v. Hamburg, p. 204. 



"Antennae not longer than the body. Dental spines simple, 

 seven or sometimes eight in number, the innermost small. The 

 superior claw armed with four or five teeth, .the inferior claw 

 lanceolate. Length about four millimeters. Denuded of its 

 scales the animal is bright yellow in color." Taken in 

 Tschuktsch Lande. 



This species appears to be very abundant throughout the 

 state, and is the only species I found out of doors, T. niger oc- 

 curring only in the greenhouse. Dark leaden, with a slight 

 purplish metallic reflection when seen alive with undisturbed 

 scales. While I feel no doubt as to the identification being 

 correct, yet a few points may well be noticed which illustrate 

 the variability of the species. The type seems, by comparison 

 of a very large number of individuals, to have four denticles on 

 the superior claw of each pair of feet, but in not a few instances, 

 the claws of the first pair showed but three denticles. The 

 inferior claw is more slender in the second and third pairs 

 than in the first. In the first pair the inferior claw often shows 

 a very minute inner denticle, which may sometimes be detected 

 even in the other two pairs. The dental spines would be some- 

 what perplexing if only a few individuals were at hand, but a 



