96 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



ON THE GENUS EXORISTOIDES COO. (TACHINID/E). 



BY W. R. WALTON, Bureau of Entomology, 

 Cereal and Forage Insect Investigations. 



In following the work of the late Mr. D. W. Coquillett in the 

 Muscoidean flies, the fact soon becomes obvious to the student 

 that he sometimes brought together under one generic name 

 (often by means of artificial characters) several rather widely 

 related forms. This indeed was his usual method of procedure 

 where the material before him was meager and yet seemed of 

 sufficient interest to merit description. I am personally in favor 

 of this system because it obviates the danger of making unnec- 

 essary generic names and still permits the recording of the spe- 

 cific descriptions. These can usually be made broad enough to 

 include any and all characters which may subsequently prove 

 to be of generic importance. 



The genus Exoristoides 1 Coq. is evidently of this character. 

 Mr. Coquillett 2 has designated the species jolmsoni as the geno- 

 type. Additional material of the other two recorded species has 

 recently fallen into my hands. Specimens of Exoristoides harring- 

 toni s Coq. collected at Plummer's Island, Md., by Dr. A. K. 

 Fisher, and at Dead Run, Fairfax County, Va., by R, C. Shan- 

 non, show structural characters which demonstrate beyond a 

 doubt that the species is not congeneric with the genotype. 



The other species, namely, slossonce Coq. seems doubtfully con- 

 generic with johnsoni Coq., the shape of the third antenna! joint 

 is quite dissimilar, and the scanty setulse of the first vein are 

 sometimes missing in the male. When this occurs the species 

 will run to Exorista in Mr. Coquillett's table. Whether or not 

 the missing setulse have ever existed is difficult to decide. But 

 perhaps the species would better remain where it is for the pres- 

 ent. The genus is characterized by Mr. Coquillett as follows: 



"First vein partly bristly, frontal bristles descending below 

 base of antennas, vibrissae on a level with front edge of oral mar- 

 gin, antennae reaching lowest fourth of face, eyes distinctly hairy, 

 head at vibrissae distinctly shorter than at base of antenna?, sides 

 of face bare, apical cell open, facial ridges bristly on lower fourth, 

 third vein bristly more than half way to small crossvein." The 

 following notes are made from the genotype: Apical cell ending 

 in costa distinctly before wing tip, fifth vein destitute of setula 



1 Rev. N. Am. Tach., p. 31. 

 Type species of the N. A. Diptera, p. 544. 



This species was originally designated as the type of a new genus in 

 the present paper as read February 4th, but was anticipated under the 

 generic name Hotnalnctia Townsend in Proc. Biol. Soc. Wafh., Vol XXVIII 

 pp. 19-24, February 12. 



