COLLEMBOLA OF THE FAMILY ISOTOMIDAE 



15 



segment stout, elliptical, with slender curving olfactory setae. Sense 

 organ of third antenna! segment with a pair of papillae, each in a 

 shallow pit. Thorax long, three-fifths as long as abdomen, with 

 tergites in relative lengths about as 10 : 18 : 15. Abdominal segments 

 without ankylosis, in relative lengths about as 13: 14: 13: 15: 13: 9; 

 fourth segment thus a little longer than the third. Anal segment 

 simple, unmodified. Anus caudal. Unguis (pi. 2, fig. 18) feebly 

 curving, simple, untoothed. Unguiculus minute, lanceolate, acumi- 

 nate, untoothed, extending about one-third as far as unguis. Tenent 

 hairs absent. Ventral tube (pi. 2, fig. 19) simple, with a pair of hemi- 

 spherical vesicles, side by side. Furcula (pi. 2, fig. 20) small, appended 

 to the fourth abdominal segment and extending slightly beyond it. 

 Manubrium stout, not tapering, roimded apically, about twice as 

 long as dens plus mucro, with several short stiff dorsal setae. Dens 

 and mucro confluent. Mucrodens gradually narrowing from the 

 base, smooth dorsally, with three short stiff dorsal setae; mesally 

 with a pair of narrow cliitinous basal ridges. Mucro subequally 

 bidentate; apical tooth hooked; anteapical feebly hooked. Clothing 

 of sparse minute equal stiff simple setae, longer and more numerous 

 posteriorly; sensory setae longer, stiff, outstanding, simple, in a row 

 across the middle of the body segment; longest and most numerous 

 on the anal segment. Integument sm.ooth. Length, 0.75 mm. 



Remarks. — Folsomides parvus differs from F. parvulus Stach chiefly 

 as indicated in table 1. 



Table 1. — Cojnparison of Folsomides parvulus and F. parvus 



F. parvulus was taken in Hungary under a large stone on moist soil 

 in a farmyard near a cow bam. The five cotypes of parvus were 

 found in Douglas fir soil, at an elevation of 8,500 feet. 



In Homer, 111., May 13, 1924, under a log on damp bottomland, I 

 found a single specimen of a species of Folsomides that is extremely 

 close to Stach's parvulus. Additional material is necessary, however, 

 for definite determination. 



Cotypes.— U.S. 'N.M. no. 42993. 



Distribution. — Recorded as follows: 



Colorado: Eastern slope of Pikes Peak, July 1, 

 Goldsmith, 



Engelman Canyon, G. W. 



