204 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



Other times much intermixed with yellow ; the same maybe said of the 

 black i)i]e of the front. The black pile of the posterior part of the ab- 

 domen is sometimes a little intermixed with reddish, but in none do I 

 find any but black i^ile on the second segment, a fact which will readily 

 enable the species to be distinj^uished from 21. posticata. 



In the synonymy of the species there has been much confusion. The 

 first one Avho published anything in regard to American specimens was 

 Ma(;quart. He, unfortunately, from their close resemblance, supposed 

 the single female specimen which he examined to belong with the male 

 type of Fabricius' Uristalis posticatus, at that time in Bosc's museum, 

 at Paris, and which he used in describing the species. In the ])resent 

 species the eyes are bare, while in Fabricius' types the eyes are pilose, 

 according to Macquart ; this, together with the fact that the base of 

 the abdomen is never yellow pilose (the sparse light hairs on the first 

 segment are very inconspicuous), renders it certain that the present 

 cannot be Eristalis posticatus Fabr., as has been supposed by later au- 

 thors. On the other hand, there can hardly be any doubt that the spe- 

 cies described by Say as Milesia harda (male) is the true E. posticaUis 

 of Fabricius. 



The description of cimbiciformis as given by Fallen does not quite 

 agree with this, and comparison is needed with European specimens 

 before the identity can be actually settled or denied. Loew believed 

 the species to be the same. 



The flight of this fly is a little peculiar, and will enable one to readily 

 distinguish it from its very near ally, M. posticata. It flies with a loud 

 buzz, going here and there, in and about the patches of flowers. 



Mallota Sackeni. (Plate VIII, tig. 14.) 



Mallota posticata Osten Sacken, West. Dijit., 338. 

 Mallota Sackeni Williston, Proc. Am. Phil. Soc, sx, 324. 



Habitat. — Washington, Texas! 



S . Length, 14°"". Closely allied to 31. cimbiciformis, but diflers in 

 the presence of a dark brown spot on the wings, and in the eyes of the 

 males being distinctly separated. 



Face black, covered with thick light yellow pollen and pile, a broad 

 median stripe and the cheeks shining. Antennae black, the third joint 

 more brownish, the angles apparently less rounded than in the i)reced- 

 ing species. Frontal triangle covered with the same dust and pile as 

 on the face, except in the middle where it is shining. Eyes bare, con- 

 vergent below the ocellar triangle, but separated by a very distinct in- 

 terval. Thorax black, thickly covered on the dorsum, scutellum, and 

 jjleurse with erect, furry, light yellow pile ; scutellum light yellow. Ab- 

 domeu black, shining, clothed with black pile ; on the first segment 

 slightly intermixed with light colored. Legs black ; extreme tip of 

 femora, base of tibiae, and the tarsi, obscure yellowish. Hind femora 

 much swollen and bent, hind tibiae compressed. Wings hyaline with a 



