Entomology of the Illinois River. 203 



in length to width of the prothorax at base; fourth seg- 

 ment a little shorter; remaining segments except last two 

 equal and distinct, about twice as long as the thoracic. 

 A dorsal small bare spot, at base of a long erect brown 

 seta, on middle of first four segments, and the posterior 

 division of remaining ones, except last. 



Last segment [Fig. 30] whiter on posterior surface, 

 which bears four narrow elongate lamelliform appendages, 

 black and transversely striate within, with narrow pale 

 margins, their exterior surfaces whitish fuscous, their 

 margins densely fringed with long fine brown hair, that 

 from neartheouterendsvery long; fringe continued across 

 intervening spaces, so as to enclose completely the stig- 

 matal field. The lower pair of appendages are below 

 the stigmata, their bases connected by two dark brown 

 streaks angulated forwards at middle; they are about 

 as long as the apical diameter of the segment and the 

 apical part of their fringe is two or three times as long; 

 above these on each side are the other two, about one 

 third as long, their bases partly surrounding posteriorly 

 the large pale testaceous stigmata, with large dark 

 brown centers. Exteriorly, the lower pair bear several 

 black setae, and the upper pair a single seta near tip. 

 Below these appendages are two short setiferous fleshy 

 tubercles. Surrounding the anal opening beneath are 

 four long tentaculiform appendages, about as long as 

 the last two segments, the two anterior dire-^ted later- 

 ally ; the posterior, backwards and outwards. 



Papa [Fig. 31] . — Length 10-13 mm., diameter about 

 1.5 mm. Subcylindrical, slightly depressed, subopaque; 

 thorax slightly thicker at middle, reddish brown to 

 black; abdomen dirty whitish, surface with light fus- 

 cous-brown transverse bars above and below. Pro- 

 thorax with a pair of dark brown or black respiratory 

 tubes, near anterior margin, not distant, about as long 

 as the distance from their bases to the apex of the first 

 abdominal, finely annulate, curving downward and in- 



