Entomology of the Illinois River. 261 



die. The middle pair of pale vittse are more conspicuous 

 anteriorly; all the lines are distinct at the sutures, and 

 obscured on the disks of the segments. The pale vittae 

 are all continued, at their relative distances, to the mid- 

 dle of the last segment, where thej^ fade out more or 

 less completely. 



Beneath, with the lateral margin and six parallel nearly 

 equal straight vittae brownish, these markings nar- 

 rower and more distinct at the sutures. On both dorsal 

 and ventral surfaces is a double row of blackish points 

 in each suture, usually concealed by the overlapping of 

 the segments, and two or three short rows of similar 

 points, converging at each end, on the disk of each seg- 

 ment near the lateral margin, the outer row on the last 

 segment prolonged nearly to its tip. Surface finely 

 granulate, thickly covered with minute peltate scales, 

 becoming setaceous near dorsal line, with a few scatter- 

 ing hairs. Spiracles on upper side of lateral margins of 

 segments 1 and 4-10; brownish, all but the first minute. 



Head small, subopaque but not granulate except 

 basally beneath, more or less longitudinally striped, 

 -dark brown at middle beneath; middle lobe rather 

 strongly sulcate above, back of the eyes; clypeus not 

 notched ; antennae very small, basal joint curved, latter 

 brown apically with two minute joints on its truncate 

 apex; eyes small, dark, slightly prominent. 



On the median line beneath, on segments 9 and 10, is 

 a short distinct narrow smooth space, extending from 

 near the base one fourth or one third of the length of 

 the segment, minutely elevated and opaque along mid- 

 dle. At the middle of the ventral hind margin of these 

 two segments is an approximate pair of minute dark- 

 brown hooks, their points curving forwards, each often 

 accompanied by one or more accessory hooks, especially 

 on the tenth segment. Last segment with sides almost 

 parallel to near middle, thence tapering slightly to apex. 

 Beneath sulcate beyond anal slit. Piliferous spots some- 

 v/hat inconspicuous. Apical fringe short, plumose. 



