164 Psyche [October 



vein, he says: "In some species the venation mentioned is inclined 

 to be variable in different or even in the same specimen." 



Another variable character is referred to in Dr. Back's key to 

 the species as "fourth posterior cell petiolate at the base or fourth 

 posterior cell sessile or subsessile." L. pictipes may be either 

 sessile, subsessile or with a short petiole. L. annulatus shows a 

 similar variation although more rarely petiolate. One specimen 

 of L. pictipes has the discal cell open on the left wing and another 

 has an adventitious cress- vein in the second submarginal cell of 

 the left wing. A specimen of L. badius and another referred doubt- 

 fully to L. incisularis, have a similar vein in the second posterior 

 cell on the left and right wing respectively. An undetermined 

 species has an adventitious cross-vein in each of the second poste- 

 rior cells, and one in the second submarginal cell of the left wing. 

 These examples are given to show possible mutations. The type 

 of L. badius has the basal third of the wings subfuscus. This is 

 only distinctly marked in one of the fifteen specimens. 



THE LIFE HISTORY OF THRYPTICUS MUHLENBER- 

 GLE SP. NOV. (DIPTERA). 



By O. A. Johannsen and C. R. Crosby. 

 Cornell University, Ithaca, N. Y. 



On April 21, 1909, while examining some Muhlenbergia syl- 

 ratica on the shaded bank of Cascadilla Creek near the Cornell 

 University Campus, Ithaca, N. Y., we noted that many of the 

 stems were broken squarely off. The tip of the cavity was plugged 

 with frass, and in each case a slender dipterous larva was found 

 just below the plug. A number of these larvae was taken from the 

 straws and placed on cotton in a vial for rearing. By May 4, 

 pupation has taken place. An adult fly was found alive on May 

 29. Again on May 5, 1910, similar pupae were found in Muhlen- 

 bergia stems that had been collected about two weeks previous. 

 Adults emerged from this material on May 24. 



The flies were at first thought to be T. willistoni which they 

 closely resemble, but subsequent study has convinced us that 

 they are a new species. In order to get fresh material in all stages 



