40 COLLEMBOLA OF MINNESOTA 



surface of the water flatwise. The body is considerably shortened 

 for a Podurid. There are no anal horns present, and no post- 

 antennal organs. The legs are strong and longer than in 

 Achorutes, and bear no clavate hairs, though there is a long 

 hair in the position of a tenant hair. There is no inferior claw 

 present, but the single claw is long, strong and unarmed. 



Our single species is that upon which the genus was found- 

 ed, and is perhaps the most cosmopolitan of all the Collembola 



aquatica, 93. 

 Genus Xenylla Tullberg 1869. 



I believe this is the first record of this genus in the United 

 States. The genus is not a large one. Its position would 

 seem to be inferior to Achorutes, from w 7 hich it has perhaps de- 

 generated. Xenylla is characterized by its slender body, the 

 abdomen being somewhat fusiform, as in Achorutes, but less 

 stout ; the absence of the inferior claw as well as of the postan- 

 tennal organ ; by its having the ocelli reduced to ten, five in each 

 eyespot ; the presence of anal horns and by the small, weak 

 furcula. The single species found in Minnesota appears to be 

 quite new and its slender form suggests the name"gracilis." 



gracilis, 95. 



Genus Friesia Dalla Torre 1895. 



This genus is represented in Sweden and England by the 

 type species. F. mirabilis Tullberg, which was the only species 

 known hitherto. Whether ours is a true Minnesota species or 

 only a sojourner here, I cannot say, for it has only been found 

 in the greenhouse. 



The characters of the genus are the absence of the inferior 

 claw and of a post-antennal organ, and the unique presence of 

 three anal horns. The body is stout and the furcula extremely 

 short and thick. caldaria, 95. 



Family Aphoruridae. 



These insects are at the very foot of the ladder of Collem- 

 bolans. Rather slow-moving, sluggish, dark-loving creatures 

 they are, living in the soil, in moist, decaying wood, etc. A few 

 species live on the surface of the water, both salt and fresh. 

 The Aphoruridae are in some ways less degenerate than some 

 of the lowest Poduridse. 



