COLLEMBOLA OF MINNESOTA 41 



The most characteristic point to be noted is the absence of a 

 furcula. The head is held nearly horizontal. Th. I is apparent 

 from the dorsal side. In some of the genera the feet bear one 

 claw, in others, two. The cuticle is usually quite plainly gran- 

 ular. In most cases a post-antennal organ is present, consisting 

 of a ring of raised tubercles situated in a slight hollow. We have 

 five genera in this family. 



Key to the Family Aphoruridae. 



1. a. — Dorsal side of the body with large, warty protuberances. 



Abdomen ending- in four rounded tubercles. Post-an- 

 tennal organs present or absent. Genus Neanura, 42. 

 b. — Dorsal part of body without such protuberances. 2. 



2. a. — Pseudocelli present. Post-antennal organ nearly pres- 



ent, generally elongate. Anal horns o or 2. Feet with two 

 claws. Genus Aphorura, 41. 



b. — Pseudocelli absent. Feet with but one claw. 3. 



3. a. — Post-antennal organ absent. Anal horns wanting. 



Genus Anurophorus, 42. 

 b. — Post-antennal organ present. Anal horns wanting. 4. 



4. a. — Ocelli absent. Mouthparts produced cone-like beneath 



the head, mouth opening in a narrow transverse slit. 



Genus Aphoromma, 42. 

 b. Ocelli present. Mouth-parts not produced conelike. 



Genus Anurida, 42. 



Genus Aphorura MacGillivray 1893. 



The Aphoruras are small, white, slender insects, somewhat 

 flattened, and are often very abundant in rotten wood, in loose 

 soil, or imder stones. They are characterized by the absence of 

 eyes, and the presence of the inferior claw which the other 

 Aphoruridse lack. Our two species, though appearing the same 

 to the naked eye, are easily distinguished. 



Key to the Genus Aphorura. 



a. — Without anal horns. Each post-antennal organ com- 

 posed of 14 to 16 tubercles. Length i mm. 



inermis, 96. 



