134 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



(fig. 8), the claws of male distinctly divided at apices as shown in the figure, 

 base sharply produced. Posterior branch of cubitus distinctly deflected 

 near its apex, then running straight to margin of wing; posterior margin of 

 wing with a distinct fringe, which is very long at anal angle but becomes 

 gradually shorter as it nears the apex; the cubitus forks very slightly 

 beyond the vertical line of the cross vein. Length, 2.5-3 mm. 



Three larva? of this species were taken March 16, 1914, in a small 

 stream which enters Salt Fork near St. Joseph, 111. They were 

 placed in glasses containing water from the city supply, mixed 

 with a little creek water in which they had been brought to the 

 office. They were for some time unable to accustom themselves 

 to the new conditions, there being evidently an excess of oxygen 

 in the city water, 1 and, along with some larvae of Orthodadius 

 nivoriundus Fitch, they repeatedly came to the surface, where they 

 remained partly above the water film. I considered that this 

 coming to the surface was due to an abnormal buoyancy caused 

 by the formation of air bubbles on parts of the bodies of the 

 larvae which made it impossible for them to remain below water. 

 This was undoubtedly partly the reason, since whenever the body 

 became coated with a number of the bubbles the specimen came 

 to the surface without any apparent effort on its part, and seldom 

 succeeded in diving below upon being touched, as they very 

 readily do under normal circumstances. Even when the surplus 

 oxygen was no longer visible in the form of bubbles the larvae 

 were restless and almost as often at the surface as beneath the 

 water; but gradually they either became accustomed to the con- 

 ditions or the conditions changed sufficiently to suit them, for 

 they settled down in the mud and dead leaves which had been 

 placed in the glasses. Here they formed burrows which they never 

 left unless disturbed. They fed upon the decaying leaf tissue, 

 generally, by protruding the anterior half of the body from either 

 end of the burrow, evidently being able to turn around within it. 

 Pupation took place within the burrow, but soon after the trans- 

 formation the anterior half of the pupa was protruded, and thus 

 remained until shortly before the emergence of the imago, when it 

 was released entirely and, coming to the surface, after a few 

 quick jerky motions the fly rapidly emerged. One specimen of 

 lundbecki remained from Monday till Thursday morning in the 

 larval stage, emerging from the pupa on Saturday morning. 

 Emergence took place very quickly, occupying not more than 

 three seconds. The other specimen which I succeeded in rearing 

 was rather longer in the pupal stage, pupating on Friday and 

 emerging on Monday morning. Both the specimens reared are 



1 This is, I believe, abnormal, as this water is generally deficient in 

 oxygen. 



