COLLEMBOLA OF MINNESOTA 63, 



Although it has lost the power of sub-segmenting- into the nor- 

 mal number, yet the normal amount of growth-power remains 

 unimpaired by the mutilation. 



While the species is rather common, I have taken it but 

 once in great numbers. One morning after a night shower they 

 appeared by hundreds in all stages of growth on the moist sur- 

 faces of stumps in the woods, where they seemed to be enjoying 

 the moisture from the wood, and perhaps feeding on the soft- 

 ened particles of decaying wood. They moved about fitfully at 

 times, but often stopped and squatted down to bring the ven- 

 tral tube into contact with the moisture. 



Isotoma minima n. sp. 

 PI. IX, Figs 17-19; X, Fig. i. 



Light grayish-blue in color, body subcylindrical, elongate, 

 almost naked except on the fifth and sixth abdominal segments, 

 which bear some long scattered hairs. Fourth, fifth and sixth 

 abdominal segments apparently so fused as to form almost a con- 

 tinuous segment. Antenna gray, little longer than the head ; Ant. 

 IV longest, very much swollen, III much rounded, shorter than II 

 and slightly longer than I. Ocelli 16. Post-antennal organ long, 

 narrowly elliptical, slightly emarginate aong anterior edge. 



Furcula short, not reaching to ventral tube ; insertion at 

 junction of fourth and fifth abdominal segments. Manubrium 

 stout and thick. Dentes straight, not tapering greatly toward 

 di?tal end, irregularly serrulate along greater part of lower edge, 

 upper edge with a few stout, scattered hairs. Mucrones and 

 dentes together about as long as the manubrium. Mucrones 

 long and narrow, tridenticulate. the distal tooth almost straight, 

 the ante-distal tooth close to, and at right angles to it ; proximal 

 tooth smaller and set about the middle of the mucrones, point- 

 ing slightly distal-wards. Each tibia bears one long simple hair 

 in the position of a tenent hair. The claws are unarmed. 



The species may be that referred to by Schott in his Sys- 

 tematik und Verbreitung der palaearctischen Collembola as I. 

 minuta Tullb. His figure of the mucrones certainly comes 

 nearer to mine than to that given by Tullberg in his "Sveriges 

 Podurider" as I. minuta; moreover, Tullberg also expressly 

 states, as his figure also shows, that the two ante-apical teeth 



