64 COLLEMBOLA OF MINNESOTA 



are set next one another and near the end. Length, three-fourths 

 millimetre. 



This species probably occurs more abundantly than its num- 

 bers in my collection would show, its minute size and light gray 

 color lending a mimicry which shields it from all but the most 

 careful observation. It seldom jumps, seeming averse to that 

 mode of motion, but moves about uneasily when its hiding places 

 are exposed to the sunlight. I have taken it in the green- 

 house of the University, under moist boxes and flower pots, 

 where it usually lived among the faeces of a certain small mil- 

 ipede, though possibly this cooccurrence was purely accidental. 

 Out of doors it is sometimes met with under stones and damp 

 boards, usually where there is a slight layer of thin, slimy mud. 

 Not uncommonly it is taken with I. bidenticula, the light-colored 

 young of which it greatly resembles until one observes it with 

 a compound lens. 



Isotoma fimetaria (L.), Tullb. 

 PL X, Figs. 5, 6. 



1746. Podura terrestris alba. Linne, Fn. Sv. Ed. I. p. 343. 



1758. Podura fimetaria. Linne, Syst. Nat Ed. X. Prt. I, p. 609. 



1871. Isotoma alba. Tullberg, Fort, ofver Sv. Podur. p. 152. 



1872. Isotoma fimetaria. Tullberg, Sver. Podur. PI. IX, 32-33. 

 1876. Isotoma fimetaria. Tullberg, Coll. Borealia, p. 37. 

 1890. Isotoma fimetaria. Uzel, Thys. Bohemiae. p. 66. 



1893. Isotoma fimetaria. Schott, Palsearct. Coll. p. 75. 



1895. Isotoma fimetaria. Reuter, Finl. Coll. p. 28. 



1896. Isotoma fimetaria. Schaffer, Coll. von Hamburg, p. 183. 



1896. Isotoma fimetaria. Lie-Pettersen, Norgcs Coll. p. 18. 



1897. Isotoma fimetaria. Poppe & Schaffer, Coll. v. Bremen, p. 68. 

 1900. Isotoma n. sp. Harvey, Ent. News. XI, p. 552. 



Tullberg thus describes it : "Third abdominal segment 

 shorter than the fourth into which the furcula is inserted. 

 Ocelli none. Dentes nearly twice as long as the manubrium, 

 straight; mucrones bidenticulate. Length, i mm." 



Some specimens found in the state measure i.25mm., but 

 otherwise the correspondence is exact, except that the slender 

 dentes is often arcuate. Claws unarmed, no clavate hairs on the 

 tibia;. Post-antennal organ narrowly elliptical as in I. quadri- 

 ocuiata. It is a more slender species than I. quadrioculata, and 



