72 COLLEMBOLA OF MINNESOTA 



more than 2.75 mm. Found on the surface of stagnant water, 

 and on leaves and rubbish along the edge of lakes and streams 

 during the whole summer; and in winter as well, when one can 

 find a place where the snow is sufficiently melted to allow access 

 to their haunts. 



Isotoma muskegis n. sp. 

 PI. XIII. 



Dense blue-black, somewhat lighter on distal portions of 

 legs and furcula, also with a few lighter dorsal markings on the 

 body. Tubercles and abdominal horns (in the male) light yel- 

 lowish brown, giving to the body a yellow, floured appearance 

 to the naked eye. Head and body sparsely haired. Head squar- 

 ish, mouth-parts slightly protruding and light yellow. Anten- 

 nae blue-black, considerably longer than head, sparsely haired; 

 Ant. I shortest and thickest. II the longest, IV longer than III, 

 I and II together about as long as the rest of the antenna. No 

 post-antennal organ. Ocelli 16, about equal in size, 8 in each 

 eyespot. Eye spots black. Body somewhat flattened, prothorax 

 showing from dorsal side, meta-thorax broader than meso-thor- 

 ax, and of about the same length. Abdominal segments sub- 

 equal. Legs strong, third pair longer than the others, especially 

 in the tibiae. Tibise bearing two clavate hairs. Superior claw 

 with a well-marked inner tooth. Inferior claw slender, un- 

 armed. Tenaculum well-developed, its two blades each four- 

 footed. Furcula on Abd. IV. Manubrium much flattened, breadth 

 about twice as great as thickness, slightly shorter than dentes. 

 Dentes pale, rather slender, tapering but little, bearing a few 

 scattered hairs, ventral surface granular or papillated as in Po- 

 dura, to which there is also a slight resemblance in the bowed 

 form of the two rami. Mucrones about one-sixth the length of 

 the dentes, and bearing two strong teeth. Length, 2.5 mm. 



I found this species twice during the summer of 1901 in 

 marshes along the shore of Lake Vermillion, on Pine Island in 

 St. Louis Co. On both occasions they wee on the upper ends 

 of partially submerged roots, or other decaying pieces of wood. 

 They seem to live socially, hundreds being seen together. They 

 resemble the heavier species of Achorutes in habits, being rather 

 slow in their movements. When exposed to the light, they be- 



