34 COLLEMBOLA OF MINNESOTA 



the posterior end of the abdomen, geniculate ones. The claws 

 are armed with teeth. Clavate hairs are borne on the tibiae. The 

 v^entral tube is well-developed. The furcula is long, slender and 

 arcuate. The mucrones is small and bears always two strong 

 teeth : a hooked or much curved apical, and a straight, strong 

 TOoth about the center of the mucrones, and at right angles to it. 

 Besides these there is usually, if not always, a very slender basal 

 tooth which points distally, its point almost reaching that of the 

 middle tooth. In fact this type of mucrones, with but slight 

 variations, is common to the scaled genera : Lepidocyrtus, Seira 

 and Cyphodeirus, to all of which this genus is closely allied. I 

 have taken five species of Entomobrya in the state, of which 

 two are new. Some, as E. cliteUaria, are perhaps local ; but 

 others as E. multifasciata are common under bark and rubbish 

 throughout the state. None of the species live upon or about 

 the water. In certain species, color variations and gradations 

 are frequent and puzzling; and on this account many varieties 

 have been described as species. In 1883 George Brook revised 

 the genus, and, by careful synonymizing, reduced the number 

 of species then recognized to less than half. His work is not 

 universally accepted by more recent writers. 



Key to the Genus ENxoiiOBRYA. 



1. a. — Abd. IV about seven times as long as III. A large 



species, very long and slender. Length 3 mm. 



bicolor, 73. 



b. — Abd. ly not more than five times as long as III. 2. 



2. a. — Color yellow with the exception of a distinct, saddle- 



like, dark marking covering Th. Ill and Abd. I, II and 

 III. Abd IV about five times as long as III. Length 

 2 mm. clitellaria, 75. 



b. — Color other than yellow. 3. 



3. a. — Color nearly uniform purplish thoughout. No seg- 



mental crossbands. purpurascens, 76. 



b. — With segmental cross-markings. 4. 



4. a. — Yellow, with four very strongly defined dark cross- 



bands situated on Th. Ill, on the dorsal part of Abd. Ill 

 taking in the caudal edge of II, on Abd. IV, and on V 



