Ischyrosyrphus. 247 



somewhat oval, a little longer than broad, about as long as the two 

 basal joints together; arista short-pubescent. Epistoma yellow, hairy, 

 it has a slightly prominent central knob; the mouth edge retreating, 

 and the lateral mouth edges and the jowls slightly descending. Mouth 

 parts as in Syrphus; proboscis not short, the palpi somewhat long, 

 considerably longer than the lacinia, slightly clubbed. Scutellum yel- 

 low, or black with a more or less distinct yellow apex ; it has a fringe 

 below the margin. No bristles on thorax or scutellum. Abdomen 

 somewhat long, with the sides subparallel ; it has a broad basal band 

 or pair of spots, and generally narrow spots on the third and fourth 

 segments; the spots vary in colour from bluish grey to bony white. 

 The abdomen has as in Syrphus five not transformed segments in the 

 male ; the first is very short and likewise the fifth ; the fifth ventral 

 segment is partly hidden under the genitalia, so that it looks as if it 

 is unsymmetrical. In the female there are five visible abdominal seg- 

 ments. Legs, wings and squamulæ as in Syrphus, the hairs on alar 

 squamulæ not much flattened. 



The genus was separated from Syrphus by Bigot in 1882, then 

 including some species not belonging here. In 1897 Mik. (Wien. ent. 

 Zeitg. XVI, 63) founded the genus Lagenosyrphus with the species 

 now included in Ischyrosyrphus. Bigot named as type glaucius L., 

 while Mik took Uophthalmus Schin. et Egg. as type. Verrall came 

 then (1. c. 321), and I think correctly, to the conclusion that the name 

 Ischyrosyrphus must remain, 



The genus is, as said, very nearly allied to Syrphus, and it is a 

 question whether it should be kept, but I have done so, as the species 

 are easily recognised and separated from the species of Syrphus. It 

 is distinguished from Leucozona by the not descending, quite yellow 

 epistoma and the wings without band, from Eriozona by the narrow 

 abdomen and shorter third antennal joint, and from Syrphus and 

 its allies by the markings of abdomen. 



The developmental stages of the genus do not seem to be known. 



Four palæarctic species are considered as belonging to this genus, 

 two of them occur in Denmark. 



Table of Species. 



1. Scutellum yellow; anterior legs orange with only base of 

 femora black; hind tibiæ orange with a more or less 

 distinct dark ring 1 . glaucius. 



— Scutellum black or with only apex yellowish; legs black 



with only anterior knees yellowish 2. laternarius. 



