COLLEMBOLA OF THE FAMILY ISOTOMIDAE 93 



340-343) small, tridentate. Apical tooth strong, hooked. Ante- 

 apical tooth smaller than the apical, inclined or suberect. Third 

 tooth proximolateral, curving dorsally more or less and projecting 

 caudolaterally (pi. 30, fig. 343). Dens with a strong subapical ventral 

 seta projecting as far as the end of the miicro or slightly beyond it. 

 Rami of tenaculum quadridentate; corpus with two strongly curving 

 ventral setae (rarely with three). General clothing (pi. 30, fig. 344) 

 of numerous short setae, most of which are simple; the longest setae, 

 near the extremity of the abdomen, are, however, feebly unilaterally 

 spinulate. Sensory setae simple or with two or three branches 

 unilaterally (pi. 30, fig. 344), erect, scarcely longer than the inclined 

 setae. Length, 0.7 mm. 



In moderately pigmented individuals the minute specks of pigment 

 form a loose network, outlining the hypodermis cells. 



Remarks. — This species is very close to the European notabilis 

 Schaffer, of which I have studied three specimens from Finland, 

 sent to me by Linnaniemi. Both species have four eyes on each 

 side, but the arrangement of the eyes diflfers in the two species, as 

 will be seen by comparing plate 29, figure 337 (eunotabilis), with 

 plate 29, figure 338 (notabilis). In notabilis the third abdominal 

 segment is to the fourth as 46:47; while in eunotabilis the ratio is 

 56:66. In notabilis the large posterior setae of the abdomen are more 

 strongly feathered than in eunotabilis. I do not know whether 

 notabilis ever has the interocular A-shaped mark, my specimens 

 from Finland having very little pigment. In other respects this 

 species agrees with notabilis, even to the presence of feathered setae 

 on the bases of the legs. 



Isotoma eunotabilis belongs to the fauna of the soil. It is common 

 on damp ground under logs and among dead leaves. I have often 

 taken it under damp boards on grass. 



Cotypes.—V.S.N.M. no. 42967 



Distribution. — Recorded as follows: 



Illinois: Homer, February 28, March 3, 14, 25, April 2, 3, 11, 12, 14, 15, 16, 21, 



25, May 2, 3, 14, 16, June 6. 

 Wisconsin: Beloit, October, V. G. Davidson. 

 Canada: Arnprior, Ontario, November, C. Macnamara. 



ISOTOMA (ISOTOMA) FINITIMA Scherbakov 



Plate 30, Figure 345 



Isotoma finitima Scherbakov, 1899c, p. 80. — Wahlgren, 1900a, p. 367. — Remy, 

 1928, p. 65. 



Description.— Bluish white; young individuals are white. Eye 

 spots black, but eyes absent. Postantennal organs absent. Anten- 

 nae longer than the head, with segments in relative lengths as 10:15:- 

 16:25. Fourth abdominal segment about as long as the third (as 



95462—37 7 



