24 Mr. C. H. T. Townsend on Diptera 
species of Nauwstgaster occurring in North America, three of 
which Dr. Williston had before him when writing his 
‘ Synopsis of Syrphide.’ These are mentioned on pages 21- 
22 under the name of V. punctulata. Dr. Williston has been 
loth to separate the forms as distinct, on the picture of the 
wings alone ; but when material from several widely separated 
localities shows a constant pattern for each locality, supple- 
mented by differences in the thoracic vitte, I think they may 
properly be separated and accepted as good species. In con- 
nection with N. meridionalis from the Rio Nautla, therefore, 
I wish to present here the following notes on the separation 
of the forms of Nawstgaster, although three of the species 
concerned belong to the fauna of Texas, New Mexico, and 
California. 
The single female from New Mexico, from which Williston’s 
description of punctulata was drawn, is the only specimen of 
that species so far recorded. I have seen another from 
Rincon, N.M., taken by Cockerell on flowers of Chilopsis 
linearis (Cav.), DC., July 5, which agrees with Williston’s 
description in the wing picture. 
The five males from California, together with the additional 
males and females from the same place (see Will., Synop.), 
constitute another well-marked species, the specimens all 
agreeing with each other. or this species I propose the 
name unimaculata. It is distinguished by the single spot of 
the wings and the five thoracic vitte. 
The male from the Isthmus of Tehuantepec forms a third 
species, which I have considered to be the same as_meridio- 
nalis. It should be stated that I have not seen the Tehu- 
antepec specimen nor the Brazilian specimens referred by 
Williston to the same species, but that I refer them to 
meridionalis on the statements of Williston regarding the 
picture of the wings. 
A fourth species from Texas I describe below. These 
four species may be separated as follows :— 
Table of Species of Nausigaster. 
1, A single spot on the wings; five thoracic 
Vibbie SER Shs heh ig see Ohh os -oteR eee unimaculata, sp. n. 
(California.) 
Two spots on the wings, the spots not con- 
fluent ; only two thoracic vitte .......... punctulata, Will. 
(New Mexico.) 
The two wing-spots confluent, forming a more 
or less well-defined and extensive picture; 
four thoracic vitte. (Lowlands of Texas to 
Beil.) Sc cekne oe a 8s + + eee ee Ree ee 2 
