COLLEMBOLA OF MINNESOTA 39 



equals half the length of the dentes. At or near the apex of 

 Abd. VI are borne the two anal horns. Sometimes these are 

 long, sharp, curved and quite prominent ; sometimes scarcely 

 visible ; and in certain species (the Achorutes of MacGillivray) 

 entirely lacking. Our five species all have them. These chit- 

 inous horns proceed from the papilas more or less raised above 

 the dorsal surface. The Achorutes are among the snow insects, 

 several species having been found on the surface of snow-pools, 

 in early Spring. They are often found in wet places, in decaying 

 wood, under bark and stones, and on fungi, on which some of 

 them feed. 



Key to Genus Achorutes. 



1. a. — Superior claw with a tooth. Tenant hair strong. Mu- 



crones less than half as long as dentes (except A. schotti). 

 Anal horns short. 2. 

 b — Superior claw not toothed. Tenant hair feebly devel- 

 oped, not very distinctly clavate. Mucrones about half 

 as long as dentes. Anal horns long, curved and sharp. 4. 



2. a. Dentes with several sharp pointed spikes borne ventrallv 



near its distal end. Dark blue, pruinose. Mucrones two- 

 toothed. Anal horns hardly visible. Inferior claw taper- 

 ing suddenly in its distal third. socialis, 92. 

 b. Dentes without spikes. 3. 



3. a. — Inferior claw very slender, almost bristle-like. Mu- 



crones more than half as long as the dentes. 



schotti, 93. 

 b. — Inferior claw becoming bristle-like beyond the middle. 



Mucrones one-third to one-fourth as long as the dentes, 



which tapers .considerably. schneideri, 91. 



4. a.- — Uniform dark blue in color. longispinus, 90. 



b. — Light ground color, whitish beneath, covered dor sally 



with gray specks. boletivorous, 89. 



Genus Podura Linne 1758. 

 The genus Podura seems to be merely a form adapted for 

 life on the surface of the water. The bow-legged appearance of 

 the furcula reminds one strongly of the water Sminthuri : S. spi- 

 natus and S. penicillifer. And here too the mucrones is flattened 

 in such a manner as to be most efficient in leaping by striking the 



