1 86 KANSAS UNIVKRSITV QUARTRRLV. 



agreeing with Dr. Williston's description. This insect, however, 

 differs from Ac/-c\o;iossa in the direction of the ocellar bristles, which 

 are turned backwards; otherwise it seems to agree well with the 

 description of A. hesperuiariiin. Brauer and Bergenstamm place 

 much stress on this character. To illustrate, they erect the genus 

 CnepJialiodes for the reception of a s|iecimen which was a Cncplialia in 

 all respects except the direction of the ocellar bristles. In the 

 present instance I do not know whether Acrog/ossa should be united 

 with CncpJialia or not. Though I have not seen the types of 

 Acroglossa, it is evident from the description that this ocellar-bristle 

 character is all that separates the two genera. In my experience, 

 this character is not a variable one. I find but three specimens in 

 the series of Cnephalia-like forms which have the bristles proclinate, 

 and these have also short, stout proboscides, with large labeliit. In 

 Gonia these bristles are regularly curved backwards. 



In conclusion, what has been said in the foregoing pages will at 

 least indicate how much we ha e yet to learn before we can correctly 

 •appreciate the relative values of the structural characters of the 

 Tachinida;. To the non-dipterological entomologist it may seem 

 surprising that the presence or absence of a mere bristle, or even the 

 direction toward which a bristle is turned may serve to distinguish 

 not only species and genera, but even groups of genera, but the 

 student of Tachinidae is almost prepared to base species and genera 

 upon a single hair. 



