E. T. CRESSON, JR. 279 



SO.^E !VORrH AllERICAIW DIPTERA FROM THE 

 SOUTH WEST. 



BY E. T. CRESSON, JR. 



Paper I. 



ORTALID^. 



(Plate VI) 



The material treated of in this paper was collected by J. A. G. 

 Rehn and H. L. Viereck chiefly in New Mexico during the summer 

 of 1902, under the direction of the Acad. Nat. Sci., Phila. ; also a 

 few species collected in Mexico by J. F. McClendon during the 

 summer of 1903, some remarks on whose trip may be found in Ent. 

 News, Vol. XVII, p. 26, 1906. 



Ostracoccelia luirabilis Gig-Toz. 

 Guadalajara, Mexico. One S . 



RiTellia coiijuucta Lw. 



Guadalajara, Mexico. One 2 • 



Rivellia occulta v. d. W. 



Guadalajara, Mexico. One 9 . 



Stenopterina luexicana Mcq. 



Round Mt., Texas. Two S . 



These agree well with Loew's description, in his monograph, of S. 

 cterulescens Lw., which is a synonym of the above ; in addition they 

 liave the following distinct characters : the anterior and the lower 

 posterior orbits pollinose ; antennal base and the space between 

 them black ; a distinct black bristle on the posterior portion of 

 cheeks ; proboscis nearly black ; the super alar groove of thorax 

 rufous; a small callous before the wing in the dorso-pleural suture, 

 yellow or rufous; the last segment of abdomen one-third longer than 

 the penultimate; squamuhe white or cream ; legs yellow; the fore 

 coxpe yellow, silvery on the anterior surface; tarsi infuscated. 



TRANS. AM. ENT. SOC. XXXII. SEPTEMBKK, 1906. 



