Dec. 1S97.] TOWNSEND : DiPTERA FROM THE TaMAULIPAN ReGION. 171 



DIPTERA FROM THE LOWER RIO GRANDE OR 

 TAMAULIPAN REGION OF TEXAS.— I. 



By C. H. Tyler Townsend. 



The present paper is the first of a series to be published on the 

 dipterous fauna of the region of the Lower Rio Grande, in Texas and 

 Tamaulipas. The material described was collected by the writer, princi- 

 pally near Brownsville, Texas, while engaged as Field Agent of the 

 Division of Entomology, of the U. S. Department of Agriculture. 



The writer has already published, in the Transactions of the Texas 

 Academy of Science, i, pp. 71 to 96, a paper on biogeography, which 

 includes mention of the Lower Rio Grande district. This district forms 

 a part of the TamauUpan fauna, which may be recognized as extending 

 from the Nueces river region in Texas to the central or southern part of 

 the ]\Iexican State of Vera Cruz. Several months' collecting done by the 

 writer in the Lower Rio Nautla region of the State of Veracruz, since the 

 above paper on biogeography was published, has shown that that local- 

 ity must come within the limits of the TamauUpan fauna, as possessing 

 many temperate forms of insects. A considerable number of these tem- 

 perate forms may range as far south as the Coattjocoalcos river, or even 

 farther. 



It is pointed out in the above mentioned paper that at best the 

 insect fauna of Lower Rio Grande, from an examination of some 500 

 species of Coleoptera and Diptera, shows somewhat less than twenty- 

 five per cent, of Neotropical forms. Probably the percentage will run 

 lower on the examination of a greater mass of material. The district is 

 mainly Lower Sonoran ; but there is, beside the Neotropical (^Mexican 

 province of the tropical transition zone), a considerable element of 

 Aitstroriparian, and even a few Upper Sonoran forms reach down to it 

 from the west, while a maritime Antillean fauna reaches up the Mexican 

 coast line and keys to Padre Island. The fauna of this district is there- 

 fore rich in forms, as particularly evidenced by the Coleoptera so far 

 collected, for no less than five great life provinces tend here to meet and 

 intermix their constituent elements to a greater or less extent. 



For the determinations of the flowers on which the diptera men- 

 tioned in this paper were taken, I am indebted to Dr. J. M. Coulter and 

 Mr. F. V. Coville. 



SIMULIID.F. 



Simuiium tamaulipense, sp. nov. 



9 . Length, i J^ mm. Near 5. meridionale, but smaller and the outer one on 



