66 COLLEMBOLA OF MINNESOTA 



body is sparsely covered with short hairs interspersed with 

 a few longer ones. As Schott and Lie-Pettersen both mention 

 having found white specimens, it is not improbable that there is 

 a white and a colored variety. 



They are found under bark of logs and under flower pots 

 in the greenhouse. 



Isotoma bidenticula n. sp. 

 PI. X, Figs. 2-4. 



Dull blackish gray, varying from light to dark, and bearing 

 usually a brownish, though sometimes a bluish tint. Lighter be- 

 neath, also on furcula and at junction of body segments. An- 

 tennae darker, and not longer than head ; Ant. I shortest, III 

 slightly longer than II, and less than twice the length of I. 

 Ant. I and III together nearly as long as IV. Body sparsely 

 haired, the hairs being longest and most numerous on the final 

 abdominal -segment. Claws without teeth or tenent hairs, outer 

 one curved, inner one very slender. Furcula small, straight, 

 reaching only to anterior edge of third abdominal segment. 

 Manubrium rather longer than dentes and mucrones together. 

 About the middle of the dorsal edge of dentes are a few rounded 

 serrations. The same edge has, besides several short hairs, one 

 long straight hair, borne not far from the manubrium. Mu- 

 crones bidenticulate, the aoical tooth somewhat curved, the 

 other pointing a little towards the front so that they form almost 

 a right angle. The fourth and fifth abdominal segments are 

 so fused as often to appear but one. The furcula seems to be 

 borne by the fourth. Length, 1.5 mm. 



This species very closely resembles I. minima in general 

 body form, and sometimes, when young, in color as well, though 

 the tendency is more often towards a brown than a blue. The 

 post-antennal organ is of the same shape in both, but is com- 

 paratively longer in I. minima. As to comparative length of 

 furcula, antennae, abdominal segments, etc., they differ but little, 

 but a glance at the mucrones will at once separate the two 

 species. Again I. bidenticula is much the larger of the two, 

 measuring twice the length of the other species named. Found 

 under stones and bark, and under flower pots in the University 

 greenhouse. Rather common. 



