iLntoinology of the Illinois River. 247 



brownish in younger larvae, dorsal pair narrowly con- 

 nected over median line. Main internal trachese usually 

 eubparallel, sinuated, not very conspicuous, although 

 easily traceable. Stigmatal spine rarely visible. 



Fupa, cT [Fig. 52-54].— Length 30-35 mm., diameter 

 7.5 mm. Yellowi.'-h fuscous with a brownish tint, thorax 

 not paler. Palpal sheaths distinct, short, very narrowly 

 separated by a depressed space. Abdomen roughly 

 wrinkled and subopaque. Spiny friuges tipped and an- 

 nulated with black. Otherwise as in the pupa (female) 

 of T. stygius. 



A few larvae have come to my hands which are like 

 atratus except in one particular — the surface of the body, 

 especially of the anterior abdominal segments, shows a 

 fine undulate wrinkling resembling the sculpture of the 

 pupa, but smoother. As the specimens showing this ap- 

 pearance are shrunken and in bad cond^ition, I surmise 

 that it is an effect of letting the alcohol get too weak 

 and then changing to strong alcohol. 



T. americanus Forst. 

 Illinois [Le Baron Collection]. 



T. gig ant ens De G. 



Occurs late in the season. Taken from Aug. 26 to 

 Sept. 6, in Woodford, Champaign, Washington, Jackson, 

 and Union counties. Dr. Wiiliston found it extraordi- 

 narily abundant and very annoying to stock in wood- 

 lands of Fayette county, near Vandalia, in September.* 



Family STRATIOMYllD^. 



The elongate-lanceolate flattened larvae of Stratiomyia 

 and Odontomyia [Fig. 57, 59, 60] were common feat- 

 ures of the shore life wherever aquatic vegetation flour- 

 ished. They are rather large, opaque, greenish, brown, 

 or gray, obscurely striped, and are found either in the 

 water upon vegetation near the surface or floating 

 about, or crawling over the bare nmd and among the 

 matted algal growths on wet shores. Odontomyia seems 



♦Trans. Kans. Acad. Sci., Vol. X., p. 139. 



