32 COLl.EMBOLA 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. 



