118 INSECUTOR INSCITI.B MENSTRUUS 



"The ocelli/' These as a rule are very uniform in their 

 position on the frons, but in one species, Chilosia catalina, they 

 are placed well forward of the line of the posterior eye margins. 

 This is an imaginary line between the upper posterior corners 

 of the eyes, following the general direction of the posterior eye 

 margins. The position of the ocelli should prove of much use 

 in classifying the Microdontinae, as it varies a good deal ac- 

 cording to the species and even groups of species in this 

 subfamily. 



"Antennal pits separated." In the hairy eyed Chilosia the 

 lower median point of the frontal lunule extends well down 

 between the antennae ; and at the same time a chitinous pro- 

 jection of the face extends upward between the antenna and 

 meets the downward projection of the frontal lunule. Thus a 

 chitinous ridge is formed which separates the two antennal 

 pits. This is a striking characteristic of the Melanostomini 

 (Syrphinae). 



"Antennal pits confluent." There is a distinct break between 

 the frontal lunule and facial projections so that the two antennal 

 pits are confluent. 



"Pile on the head." The distribution of the pile on the head 

 is of much importance in the Syrphidae and in the above men- 

 tioned paper is used to separate the Eristilinae from the 

 Xylotinae. It can be used to fine advantage in the Chilosinae, 

 e. g., the antennal frons is pilose in all of the tuberculate face 

 forms except the subgenus Barberiella; Chilosia (sensu stricto) 

 has hairy eyes; and the Chrysogasterini and about half of the 

 species of Chilosia and one species of Cartosyrphus, sialia, have 

 the face pilose. 



"Face pilose {or hairy)." This term is intended to mean 

 (in accordance with Becker and Verrall) that the face bears 

 fairly long, distinct pile other than the very fine pollinosity, 

 and the pile on the lateral facial strips. 



"Lateral facial strips." The lateral sides of the face in 

 Chdosini have a more or less elongate groove separating a more 

 or less broad strip from the rest of the face. These have been 

 called "eye margins" by Becker and Verrall. 



