98 AMERICAN DIPTERA. 



tips; first joint of the tarsi rufous, tlie following joints blackish; tibise with a 

 preapical bristle. Halteres yellow. Wings grayish ; a black border along the 

 costa, around the tip and on the cross-veins, and blackish spots of different sizes 

 in all the cells; the costa with a row of short bristles; small cross-vein nearly 

 under the end of the first vein, and on the middle of the discal cell. 



" Hab. Mexico, Sierra de las Aguas Escoudidas in Guerrero, 

 9500 ft. (H.H.Smith). 

 " Two female specimens." 



AL.LOFHYL,A Loew. 



One fronto-orbital bristle; five dorso-central, arranged as in Helo- 

 myza; one humeral ; one propleural ; one presutural ; two notopleu- 

 ral ; no prescutellar ; two pairs scutellar; three supra alar; one 

 sternopleural ; no mesopleural. 



Head as in Helomyza, third antennal joint a little elongated, 

 • arista pubescent. 



The main distinction between this genus and Helomyza is in the 

 absence of the humeral bristle in the latter. 



Only one North American species has been brought to light. 



Allo|>Iiyla l8eTi!$ Loew. 



Length 4.7 mm. ; of wing 5 mm. 



Yellow, antennae of the same color or a little darker, third joint iufuscated in 

 the female; arista pilose. 



Head yellow; front saffron-yellow, with very delicate pubescence, eyes rather 

 large (about twice the width of the cheeks), round; cheeks straw-yellow; 

 vibrissfe very delicate. 



Thorax varying from saffron to straw-yellow, densely pubescent; .scutellum 

 bare except the ordinary four bristles; mesopleura bare; steruopleura rather 

 sparsely pubescent, with one strong bristle. 



Abdomen yellow, more or less infuscated, hypopygium of the male small. 



Wings almost hyaline, unspotted, except a little infuscation around the hind 

 cross-vein. 



Legs straw-yellow, last tarsal joint black. 



Two males and six females. Johnson : Montpelier, Vermont, 

 June 25th ; St. Johnsbury, Vermont, June 27th ; Mt. Greylock, 

 Massachusetts, June 15th ; Castle Rock, Pennsylvania, June 16th. 

 U. S. N. M.: White Mountains, New Hampshire, Morrison. Aid- 

 rich : Guemes Island, Washington, July 13th ; Mt. Constitution, 

 Orcas Island, Washington, July 7th. 



Qui^t^-VvvAYvl)^^-^ SII^IGO Aldrich, n. gen. ^ '^a^n*-*'(X^ 



(Latin, siligo a very pale kind of wheat ; feminine, accent on sec. 

 ond sylable.) 



One humeral bristle ; one propleural ; two uotopleural ; five dorso- 



