4 DIPTERA. 



4. Bibio albipennis. 



Bibio albipennis, Say, Compl. Writings, ii. p. 69 * ; Wiedem. Aussereur. zweifl. Ins. i. p. 80. 

 Hab. Noeth Amekica, Atlantic States 1 . — Mexico, Northern Sonora (Morrison). 



I am in doubt whether six males and two females from Northern Sonora belong to 

 this species or to Bibio hirtus, Loew, Centur. v. 2 (California). I have before me 

 several male specimens from Yosemite valley, the long, shaggy hairs of which agree 

 with Loew's description of B. hirtus, but much less with the specimens from Sonora. 

 The wings of the latter are distinctly greyish, while Loew says of B. hirtus, ? , " alse 

 non cinereae." For this reason I prefer to identify the specimens from Sonora with 

 B. albipennis. 



5. Bibio xanthopus. 



Bibio xanthopus, Wiedem. Aussereur. zweifl. Ins. i. p. 80 l . 



Hab. Noeth Ameeica, Atlantic States 1 . — Mexico, Northern Sonora (Morrison). 



A single male. As I have no specimens from the Atlantic States before me, I am 

 not quite certain about the identification. 



DILOPHUS. 



Dilophus, Meigen, in Illiger's Magaz. ii. p. 264 (1803). 



1. Dilophus melanarius. 



Dilophus melanarius, v. d. Wulp, Tijdschr. &c. xxiv. p. 146 '. 



Bab. Mexico 1 . 



Van der Wulp's specimens were from Mexico. Four females from lrazu, Rio Sucio, 

 and Cache in Costa Rica (Bogers) agree with the above-quoted description ; the identi- 

 fication, however, of black Dilophi is always difficult and subject to doubt. 



2. Dilophus ? 



Hab. Nicaeagua, Chontales (Janson). 



Two specimens from the above locality differ from the preceding species in the head 

 being still longer, and the wings dark yellowish-brown, less blackish. Other differences 

 may perhaps be discovered in better preserved specimens. 



The following other Bibionidse from Mexico have been recorded (there are none 

 from other parts of Central America) : — 



Bibio canadensis, (Macq. X) Bellardi, Saggio &c. i. p. 18. 



criorrhinus, Bellardi, 1. c. i. p. 17. 



fuligineus, Bellardi, 1. c. i. p. 19. 



