226 BULLETIN UKITED STATES GEOLOGICAL SURVEY. 



jSTorth America north of Mexico, distributed as far as possible among 

 the genera where they belong, will be found on the following pages.* 



An analytical table of all the genera hitherto found in the United 

 States is also given. 



From the very circumstance that the Bomhi/UdcB are one of the most 

 numerously represented families of Dipterii in the Western Territories, 

 it follows that it would be premature now to attempt any generalization 

 about their geographical distribution. The following remarks, based 

 upon the existing data, are therefore only provisional. 



Among the group of Anthracina, the genera Anthrax^ Exoprosoioa^ 

 and Argyramxha are abundantly represented both in the Atlantic and 

 Pacific States, but probably more so in the latter. The new genus 

 Bipalta, with a single species, occurs in Colorado and in California as 

 well as in Georgia. 



The North American species of the group Lomatina, which I have 

 seen, have the general appearance of Anthrax, but, at the same time, a 

 very short prsefurca, with the small cross-vein far beyond its end, and 

 the eyes contiguous in the male. They differ from the Bombylina in the 

 globular shape of the head, the very large size of the frontal triangle 

 of the male, and often in the Anthrax-like antennse, more or less distant 

 from each other at the base. The genus Oncodocera, with 0. leucoprocta 

 from the Atlantic States, belongs here. I have introduced the new 

 genus Triodites, with one species from California and Utah. I possess 

 a species from Colorado, which will require the formation of a new 

 genus ; I do not describe it at present. Anisotamia eximia Macq. ( = 

 Anthrax valida Wied.) from Mexico is related to Oncodocera. From 

 Mr. Loew's itatements about Aphoehantus and LeptocMlus, both new 

 genera, with a single species from Texas, I judge that they likewise 

 belong to this group. The Stygia elongata Say [Lomatia elongata Wied.) 

 is evidently not a Lomatia, and perhaps not a Bombylid at all. I have 

 never seen it. 



The Toxophorina are represented as yet only by one Toxophora from 

 California and by several from the Atlantic States. A single Systropus 

 occurs in the Atlantic States. 



The BomhyUnaoxe represented by the genera BotnhyUus, iSystoechus, and 

 Sparnopolius. From Sysioechus I. have separated the genus Anastoechiis 

 which also occurs in Euroi3e. Pantarbes nov. gen., with a single species 

 from California, is not unlike MuUo. Lordotus Lw., with one species, 

 occurs in Colorado, Wyoming, and Texas, as well as in California. 

 Comastes nov. gen., with one species from Texas, is a very original and 

 interesting form. Floasis represented by seven species from California, 



* In identifying species from the United States, the descriptions of species from the 

 West Indies and Mexico must not be quite neglected, as some of these species may 

 have a wide northerly range. Lists of these species will be found in my Catalogue of 

 the Described Diptera of North America, Smithsonian Institution, 1858. The species 

 published since will be found in Loew's " Centuries ", in Jaeuuicke's " Exotische Dip- 

 tern ", and in Bellardi's "Saggio". 



