COLLEMBOLA OF MINNESOTA 95 



resemble in form. In both cases the furcula is dorso-ventrally, 

 instead of laterally flattened. 



Xenylla gracilis n. sp. 

 PI. XI, Figs. 12-15. 



Rather dark blue above, paler beneath. Body slender, fu- 

 siform, head narrow in front, becom.ing broader between the 

 eyes and then narrowing again. Thorax narrower than the head. 

 Abdomen gradually broadening posteriorly till the fourth seg- 

 ment, after that narrowing rather abruptly, the fifth and sixth 

 segments being much narrower. The sixth is blunt on the end, 

 and bears two supra-anal spines on separated papillae, the spines 

 not longer than the papillae themselves. Claws short, unarmed, 

 tibiae with two clavate hairs. Ocelli placed as usual in this genus. 

 Antennae hardly longer than the head. The second, third and 

 fourth segments about equal and somewhat longer than the first. 

 The third and fourth are broad. The mucrones is of a different 

 form from any described or figured so far, the recurved hook at 

 its end being quite characteristic of the species. The dentes and 

 mucrones together are about one-third longer than the claw. 

 Length, .9 mm. Taken rather rarely in damp places under boards 

 along the Mississippi bottom lands, where they live socially. 



Friesia caldaria n. sp. 



PI. XI, Figs. 16-18. 



Purplish blue above, paler beneath. Eye spots conspicu- 

 ously black. Body short and thick, with antennae, legs and fur- 

 cula to correspond. Head triangular in outline as seen from the 

 side. Claw rather short and stout, tibiae with two clavate hairs 

 nearly as long as the claw. The fifth and sixth segments of the 

 abdomen bear dorsally several clavate hairs. The furcula is 

 more rudimentary than in any other genus, the manubrium being 

 very short and broad, the mucrones hooked at the end, and two- 

 thirds as long as the dentes. Dentes and mucrones together are 

 but little longer than the larger anal horns. The three anal horns 

 are situated in a triangle, the hindmost one being median, and 

 somewhat smaller than the other two. Each one is set on a .short 

 papilla. There is present a well-developed tenaculum, with two- 



