12 THOMAS SAY FOUNDATION 



cephalon is strikingly developed backward in the 

 genus Sarothromyia (Fig. 7a). 



Tlioraoc. — The chsetotaxy is explained, for con- 

 venience of reference, in connection with figure 14G, 

 in the explanation of the plates. 



The expression "3-5 black stripes" means that 

 there are three principal, distinct stripes, and outside 

 of these one shorter, less distinct, on each side. 



Abdomen. — The genitalic characters are ex- 

 plained in the next section. 



Legs.- — A male character of some importance is 

 the frequent presence of a comb on the lower hind side 

 of the middle femur near its tip ; this consists typically 

 of a row of sliort, flattened, blunt bristles, close to- 

 gether; there may be only five or six bristles of this 

 character. It diminishes through a series of species 

 so gradually that it is hard to say where it ceases to 

 exist. None of the females possess it. 



JVings. — At the extreme base of the costa are 

 found two scales, one so close to the thorax as to be 

 somewhat difficult to see in many specimens. These 

 are epaulet and subepaulet. The latter, which is the 

 outer, is easily seen, and is always pale; the former is 

 usually quite black, but in the liavinia group it is 

 reddish-yellow, a minute but seemingly good char- 

 acter. 



The costal segments are numbered, following 

 Bottchcr, so that the first segment is before the hu- 

 meral crossvein, the sixth and last measures the open- 

 ing of tlie first posterior (or apical) cell. 



The costal spine, when present, is at the tip of 

 the auxiliary vein. 



The Genitalic Chaiiacteks. 



One could hardly believe without experience 

 how easy and how positive the identification of species 

 becomes in the Sarcophagida^ by the aid of the male 

 genitalia. The prime object of the present paper is 

 to impress this fact and open a new field for taxo- 

 nomic workers. There is no reason why in the course 

 of a few years there may not be dozens of correctly 



