392 C. R. OSTEN SACKEX'S PRODROME 



segment shows four longitudinal spots on ^yellow ground ; sometimes these spots expand at 

 both ends in such a manner as to leave only a longitudinal yellow stripe in the middle, and 

 a round yellow spot, on black ground, each side ; the fourth segment is colored like the 

 third, so that in some cases the al^domen shows two longitudinal black stripes, reaching 

 from the scutellum to the posterior margin of the fourth segment, and two lateral stripes 

 on the third and fourth segments ; in other cases (and, upon the whole, more frequently), 

 the third and fourth segments may be described as black, with a yellow median stripe and, 

 on each side, yellow spots, a pair on each segment. The last segments are black, Avith yel- 

 low hind margins, the fifth sometimes with a yellow median line. Venter yellow ; third 

 and fourth segments with black spots in the middle (which are nearly obsolete in some 

 specimens), and blackish lines on the sides ; the fifth and following segments black, 

 with yellow margins. Legs as In C. monianus and also variable as to the extent of the 

 black color. Wings : both basal cells hyaline, the brown color encroaching but very little 

 upon either of them ; crossband not quite filling out the fourth posterior cell, and leaving a 

 hyaline space at its distal end and along the intercalary vein ; a brown shade on the last 

 section of the fifth vein is hardly perceptible ; the hyaline triangle between the crossband 

 and the apical spot entirely separates both and reaches the costa with its ajjex. 



Ildh. Pennsylvania; Massachusetts; White Mountains, N. II. (Scudder) ; Canada 

 (Couper); Kansas (Al. Agassiz). Twelve female specimens. 



22. Chrysops fallax n. sp. 



5 . Apical spot scpni-ated from tlie crossliand l)y tlif tip of the hyaline triangle, which almost reaches the 

 co^ta; both bisal cells hyaline; (he crossband re((cJu's the posterior margin. Facial callosities reddish or 

 brownish, third and fonrth .abdominal segments with four black longitudinal spots, alternating with yellow 

 si)aces, the black sometimes coalescing in such a way as to leave but a yellow longitudinal stripe in the middle. 



Length, 7-7.5 mm. 



Female. Very like C. hlhirls, but with the following, apparently constant, difterences : 

 it is smaller; the end of the crossband fills out the fourth posterior cell, or very nearly ,so; 

 although the hyaline triangle between crossband and apical spot crosses the second longi- 

 tudinal vein, forming a large hyaline spot in the marginal cell, still a connection is left be- 

 tween the crossljand and the apical spot, in the shape of a narrow brown shadow ; the cloud 

 on the last section of the fifth vein is somewhat more distinct ; on the abdomen, the black 

 sjiots under the scutellum, sepai'ated bij a yelloio ftpace in C. hllaris, are here coalescent 

 (this seems to be a very constant character); the converging black lines on the second seg- 

 ment are sometimes coalescent anterloi'ly; the facial callosities are usually red, often brown- 

 ish on their lower half; the cheeks are also variable, from reddish to l)lack. The abdomen 

 is like that of C. hllaris, and shows the same variations as in that species; in some speci- 

 mens the third and fourth segments, except a yellow stripe in the middle, and a yellow hind 

 margin, are entirely black. 



Male. Similar to the female ; the proximal ends of the basal cells somewhat infuscated ; 

 thorax with erect, yellowish hairs; third and fourth abdominal segments (in the two speci- 

 mens before me), yellow, with four black spots ; the following .segments black, Avith yellow 

 hind margins. 



