A Monograph of Egyptian Diptera. 75 



generally the hairs are found on a limited space of the upper 

 part, except in E. t&nax, where the hairs are much more numerous 

 and arranged in denser lines. Antennae moderate in shape and 

 length, the third joint always bearing near its base a bare arista. 

 Thorax quadrate, in some species bearing fairly conspicuous light 

 markings, and in others quite faint ones; it is more or less densely 

 pilose all over, without any trace of bristly hairs. Scutellum equal- 

 ly pilose with the thorax and usually yellowish and translucent 

 (except in E. census). 



Abdomen moderate in shape, ranging in colour from a uniform 

 aeneous-black to being largely covered with orange, white and black 

 marking's; it varies in shape and in pilosity with different spe- 

 cies. Legs almost simple in const met ion but with the hind tibiae 

 nearly always curved and with variable ciliation. Wings special- 

 ised by the closed Rl cell and by the deep loop in Radius 4 + 5 

 over the middle of cell R5, these characters distinguishing them 

 from the wings of any other Egyptian Diptera. 



SYNONYMY: — In 1857 Rondani separated off the European 

 species with a plumose arista into a limited genus Eristalis, after 

 which the species with a bare or almost bare arista have been 

 broken up into various subgenera. Rondani, who made the first 

 attempt, suggested Eristalomyia for die species which have the 

 eyes touching in the male and thus created a genus Eristalinus for 

 a single species {E. sepulchralis) in which the eyes are well separ- 

 ated in the male. This induced Mik in 1897 to further subdivide 

 the genus. He suggested that the species with a bare arista 

 should be separated into 4 genera of which the first should be 

 Eristalomyia with its type E. tenax, which has the eyes unicolo- 

 rous. As Verrall states, it was unfortunate for his generic dis- 

 tinction that E. tenax has two bands of darker pubescence running 

 down its eyes, which form its most distinctive specific character; 

 Verrall further admits that these bands are caused by pubescence 

 and are longitudinal, so that they do not traverse the generic or 

 subgeneric rank. After Eristalis, Mik separated off the species 

 with what he called "oeuli picti" which one would translate as 

 "eyes with markings," and on this basis he formed a genus Erista- 

 lodes, in which the eyes have five obscure transverse stripes, and a 

 genus Lathyrophthalmus which is distinguished from Rondani's 

 Eristalinus simply because the eyes of the male approximate in 

 Lathyrophthalmus and do not approximate in Eristalinus. 



Moi^eover the species of this genus all show a close relation- 

 ship to each other in their stout solid shape (even in the very 

 numerous European species), so that no confusion should arise as 

 to their position in this family and I cannot help agreeing with 



