24 Syrphidae. 



organ, curving down betvveen the claws or on the contrary curving 

 upwards (the penis or penis-sheath) ; below, between the claws, the 

 hypopygium is more or less incised, generally deeply, and from here 

 arise two smaller or larger, always hairy lamellæ of various shape 

 (I think placed on a small tenth segment); in a single case {Sphaero- 

 phoria) the incision for these lamellæ is very deep and closed again 

 outwards, so that the lamellæ are here sitting in the middle of the 

 lower surface of the hypopygium, I am inclined to think that the 

 down-turned side of the ninth segment is in reality the dorsal side.^ 

 In some genera {Sph aer ophor ia, Tropidla) the genitalia may look as 

 if they were symmetricai, especially when seen from above, and these 

 genera have been considered as exceptions from the rule; this is, 

 however, only apparently, the genitalia are always unsymmetrical and 

 of principally the same construction. In the female abdomen is more 

 pointed than in the male; its number of visible segments is likewise 

 varying, from four {Triglyphus) to six, but the border between trans- 

 formed and not transformed segments is here less sharp, sometimes 

 a seventh or eighth small segment may be seen; the small posterior 

 segments are otherwise generally hidden, the last terminates with two 

 small lamellæ. The ventral segments are generally well chitinized, 

 but in some cases they are rather delicate and slightly chitinized. 

 Abdomen has no bristles of any kind. Legs more or less long, in 

 most cases of rather simple shape, but they may sometimes be more 

 or less specially formed; thus the posterior or only the hind coxæ 

 or trochanters may bear spines or processes in the male, the hind 

 femora may be thickened and more or less curved, often at the same 

 time armed with a tooth or with rows of spines, either in both sexes 

 or only in the male; also the hind tibiæ may be thickened, com- 

 pressed and more or less curved, and they have always a more or 

 less pronounced incurvation near the apex on the posterior side; 

 hind metatarsus is not rarely more or less thickened. The legs are 

 always haired in principally the same way, the anterior femora more 

 or less long-haired on the posterior side and below, the hind femora 

 on the anterior side and below, sometimes also above; for the rest 

 the hairs are short; sometimes also the femora are rather short- 



* 1 think the exterior genitalia are rather homologous to those in the Dohchopo- 

 dids; hke those they are unsymmetrical and bent round, but here not from 

 the dorsal to the ventral side but from the left to the right, the ninth segment, 

 however, perhaps bent such, that its real dorsal side is turned downwards; as 

 in the Doliohopodids the eighth segment is not divided into tergite and sternite; 

 the claws I think answer to the inner lamellæ in the Dolichopodids, and the 

 hairy lamellæ to the outer lamellæ. 



