32 COLLEMBOLA OF MINNESOTA 



On neither of these points can I fully agree with him. 

 However he has certainly made available many of Dr. Packard's 

 species by redescribing them from the types, and has added not a 

 few new species. 



KEY TO THE GENUS ISOTOMA. 



1. a. Furcula short, not reaching ventral tube. Claws un- 



armed. Antennae little longer than head, post-antennal 

 organ long, narrowly elliptical. 2. 



b. Furcula reaching nearly or quite to the ventral tube. 

 Antennae considerably longer than the head. 5. 



2. a. Mucrones tridenticulate. Color light gray-blue. Ocelli 



16. Length .75 mm. minima, 63. 



b. Mucrones bidenticulate. 3. 



3. a. Entirely white. Ocelli absent. Dentes about twice as 



long as manubrium. Length 1.25 mm. fimetaria, 64. 

 b. White or pigmented. Ocelli 4 or 16. Manubrium long- 

 er than dentes. 4. 



4. a White or light blue. Ocelli 4. Length i mm. 



quadrioculata, 65. 

 b. Gray-blue or brown. Ocelli 16. Length 1.5 mm. 



bidenticula, 66. 



5. a. Dentes much longer than manubrium. Male and fe- 



male alike. 6. 



b. Dentes little longer than manubrium. Clavate hairs on 

 tibia. Color dense black. Male with prominent horns on 

 Abd. IV, and with a covering of yellow sensory tuber- 

 cles, muskegis, 72. 



6.a. Ant. II curved. Tawny yellow or white. Claws un- 

 armed. Manubrium about half as long as dentes. Mu- 

 crones tridenticulate. Length 2,33 mm. 



leonina, 67. 

 b. Ant. II straight. 7. 



7. a. Body marked with blue, green or purple. No clavate 

 hairs on tibia. 8. 



b. Bluish or greenish gray. Tibiae with clavate hairs. 

 Length 2 mm. sensibilis, 67. 



