.326 *S'. W. WilKston — North American Conops. 



My knowledge of such variations I have endeavored to supplement 

 by the study of the descriptions of foreign species, and I deem it 

 worth the while to here give a translation of Dr. Loew's very perti- 

 nent remarks upon the value of the specific characters in this genus. 



"Those specific characters have the greatest weight here, as else- 

 where, that are based upon the differences in form ; such are not 

 always easy to find, yet the shape of the antennae and antennal style, 

 the structure of the face, the length of the proboscis, the structure of 

 the abdomen and of the legs, and finally the neuration offers many 

 good characters. Next in value to these characters are those 

 derived from the yellow or white shimmering markings of the dor- 

 sum of the thorax, the pleurae and the metanotum ; so, also, from 

 the form and boundaries of the coloration of the wings, when such is 

 present. The presence or absence of yellow spots on the sides of 

 the metanotum, and the color of the sciitellum are also good charac- 

 ters. Finally, the color of the front is quite useful, when cautiously 

 employed, as it is rather changeable in many species. Much less 

 dependence is to be placed upon the characters derived from the 

 dust-markings of the abdomen ; least of all upon the coloring of the 

 body in those species that are black and reddish brown, as sometimes 

 they may be quite black, sometimes reddish brown, with more or less 

 black, or sometimes indeed quite ferruginous." (Neue Beitr., i, p. 20.) 



The following table of the American genera of Conopidas, adapted 

 from Schiner, with the aid of a considerable number of our own spe- 

 cies, will be of service to many : 



Third autennal Joint with a terminal style ; ocelli wanting. Conojis Linn. 



Third antennal Joint with a dorsal, or sub-dorsal bristle : 



Proboscis bent only at the base. Zodion Lat. 



Proboscis bent at base and near the middle, the anterior part closely folding back : 



Anal cell, short, obtuse : 



Bristle of antenna?, dorsal, proboscis not of unusual length. Dalmannia Rob. 



[Des. 

 Bristle of antennas near the end of third Joint (sub-dorsal), proboscis very long, 

 abdomen cylindrical. Stylogaster Mac. 



Anal cell, extending well toward the border of the wing, acute : 



Face much produced, inferiorly, the cheeks broader than the vertical diameter 



of the eyes, abdomen depressed, short. Myopa Fab. 



Face moderately produced inferiorly, cheeks not broader tlian the vertical 



diameter of the eyes ; abdomen mostly cylindrical and moderately long. Onconiyia 



[Rob. Des. 



