COLLEMBOLA OF MINNESOTA 69 



Although one of the most widely distributed among the 

 Isotomas, I have taken the species but a few times. When 

 once found, however, the social habit of this insect insures to 

 the collector a considerable number of specimens. They are 

 active, avoiding the light less than most Isotomas. Under 

 stones and boards in low, damp places near the edge of the 

 river, or in springy places (I have only taken them in May) 

 along the Minnesota and Mississippi rivers. 



Isotoma catena n. sp. 

 PI. IX, Figs, i5-i6b. 



This species seems to be a link in the chain which connects 

 together the two species I. palustris and I. viridis. In most of 

 its characters it approaches more nearly to the latter than to 

 the former species. It is a dirty, obscure purple above, shading 

 down laterally to a lighter tint, and showing brownish purple 

 beneath. The antennae are dark purple throughout, the legs 

 rather a weak purple. The dentes, and sometimes the legs as 

 well, show a tendency to a yellow-green tint. The head is dark 

 throughout. Like I. palustris, the mucrones is provided with 

 four teeth ; the apical one being quite small, the ante-apical very 

 large and long, (in this character resembling I. palustris, var. 

 fucicola Renter, of which Schott says: "Der zweite grosse mu- 

 cronale Zahn ist langgezogen und ueberragt die anderen be- 

 deutend an Grosse.") ; the other two are set nearly opposite 

 each other as usual. In antennae, again, it resembles I. palus- 

 tris; Ant. IV being noticeably more slender than III, and sel- 

 dom so long. Here the resemblance to I. palustris ceases, and 

 that to I. viridis begins. The claws are armed with one outer 

 and two inner teeth on the superior claw r , and one inner tooth 

 on the inferior claw. The body is covered with short, closely 

 set hairs, among which, especially on the posterior end of the 

 abdomen, are interspersed longer hairs as in I. viridis. There 

 are no tenent hairs. Length, 3.8 mm. Taken at Minneapolis 

 by Mr. Oestlund. Also by myself near Le Sueur, Minn., on 

 the high wooded bank of the Minnesota River, under the loose 

 bark of a log in May, 1899. A few specimens were found at 

 Lake Vermillion in 1901. Apparently the species is not abun- 

 dant. 



