COLLEMBOLA OF MINNESOTA 29 



II. a — Body inky black excepting lower part of anal segment. 

 Head black as far front as the eyespots. Fore part of 

 head, antennae, legs and lower part of anal segment bright 

 yellow, furcula pale. Length i mm. 



minutus, 44. 

 b. — Black, with antennae nearly so. Legs and furcula brown. 

 A white spot mediad to each eyespot. Length i mm. 



niger, 47. 



Family Entomobryidae. 

 This large family is rich in genera as well as in species. It 

 differs from the preceding in the different form of the body, 

 the general form being elongate and the segment un fused. In 

 most of the genera the antennae are four-jointed, and the anten- 

 nal segments are seldom ringed. The ocelli show the tendency 

 to atrophy in most of the genera. The prothorax is short and 

 usually more or less hidden by the projecting dorsal part of the 

 mesothorax. The feet are two-clawed, and very freqviently clav- 

 ate hairs are borne on the tips of the tibiae. The furcula is 

 found in various stages, but is usually strongly developed and 

 of very material assistance in keeping its owner out of harm's 

 way. The family contains both haired and scaled genera. It is 

 interesting to note that many instances of parallelism occur be- 

 tween species of genera which are only separated by this dif- 

 ference. Probabl}^ the family would be a more natural one if 

 we omitted the genus Tomocerus, but as a matter of convenience 

 it is regarded as belonging here. 



Key to the Family Entomobryidae, 



1. a. — Body naked or covered with hairs. 2. 

 b. — Body covered with scales. 4. 



2. a. — Antennae composed of six segments. Ocelli 12. 



Genus Orchesella, 30. 

 b. — Antennae composed of four segments. Ocelli usually 

 16. 3. 



3. a. — Abd. Ill and IV about equal in length. 



Genus Isotoma, 31. 

 b. — Abd. IV at least four times as long as III. 



Genus Entomobrya, 33. 



