E. T. CRESSON, JR. 73 



Genotype. — Musca chaerophyUi Fabricius. [Monotypic] 

 There are apparentl}^ two species and several varieties repre- 

 sented in our fauna. These two species may be separated as 

 follows : 



The diluted spot in marginal cell quadrate and regular; those in the sub- 

 marginal and first posterior cells rounded borealis 



Diluted spots irregular in shape and arrangement, generally quadrate and 

 very numerous arcuata 



Euthycera arcuata Loew (PI. I, fig. 13; pi. Ill, fig. 34.) 

 1859. Tekuioccra arcuata Loew, Wien. Ent. Monat., iii, 292. 



cf, 9. Tawny; lunule, broad pleural stripe, fore femora basally, fore 

 tibiae apically, two apical tarsal joints, brown to black. Basal two tarsal 

 joints white. Wings densely reticulated with spots which are rather irregu- 

 lar in the marginal and submarginal cells. Opaque species, with the excavated 

 median frontal stripe shining and the lunule polished. Scutellum and legs 

 more or less shining. Occiput, vertex, and frontal orbits, whitish dusted, 

 with black spots at bases of bristles, and an elongate velvety black spot at 

 the anterior fronto-orbital bristle, and another black spot between antennae 

 and eyes. Face and cheeks silvery. Mesonotum irrorated with brown 

 dots and with dorso-central series of rather distinct brown spots. Scutellum 

 browTi, somewhat shining, yellow dusted, with margin velvety black except 

 at apex, which has a silvery spot. 



Face retreating and convex in profile; second antennal joint as broad as 

 tliird. Length. — 4.5 to 8.5 mm. 



Originally described from Washington, D. C, (Osten Sacken). 



Specimens Examined. — 21 cf , 16 9 . 



New York: Ithaca, July to August, [Cornell]. Mud Creek, Tompkins 

 County, June 16-20, (MacGillivray and Bradley), [Cornell]. 



New Jersey: Haddonfield, [A. N. S. P.]. 



Penxsylvani.\: Philadelphia, June, [Cornell]. Fairmount Park, Phila- 

 delpliia. May 30, (F. Haimbach), [A. N. S. P.]. McConnellsburg, Fulton 

 County, June 4, [A. N. S. P.]. Hazleton, June 10, (W. G. Dietz), [A. N. S. 

 P.]. Swarthmore, June to July, (Cresson), [A. N. S. P.]. 



Maryland: Beltsville, June 14; Plummer's Island, June 7; Near Plum- 

 mer's Island, June 2 to July 4, (all W. L. McAtee) ; Branchville to Beltsville, 

 June 4, (E. R. Kalmbach), [all Biol. Surv.]. 



Virginia: Dead Run, July 2, (W. L. McAtee); Great Falls, May 19 to 

 June 30 (W. L. McAtee) to July 2, June 30 (A. Wetmore), [all Biol. Surv.]. 



Illinois: [no other data; A. N. S. P.]. 



Variations. — There is a variety before me of which an extreme 

 form is represented by females having the fore femora almost 

 entirely darkened, the whitish wing spots very numerous and 

 small, forming three or four longitudinal series in the submarginal 



TRANS. AM. ENT. SOC, XLVI. 



