STEATIOMYIA. 37 



1. Stratiomyia mutabilis. 



Stratiomyia mutabilis (Fabr.), Bellardi, Saggio &c. i. p. 30 1 (for the remaining literature, see O. 

 Sacken, Catal. N. A. Dipt. 1878, p. 49). 

 Hob. Mexico, Cuantla, Meztitlan (de Saussure), Cuernavaca (Truqui), Mexico city 

 (Salle) 1 ; Guatemala, San Geronimo (Champion) ; Costa Eica, Irazu 6000 to 7000 feet 

 (Bogers) ; Panama (JBoucard). — Bkazil 1 . 



It is difficult to describe, and still more so to recognize from a description, a species 

 so variable as the present. I quote Bellardi only, because his descriptions alone agree 

 with our specimens. The upperside of the abdomen of these examples is black up to 

 the anterior part of the fourth segment, the latter half of that segment, as well 

 as the greater part of the fifth, yellow ; the venter is black, but the posterior 

 margins of the segments have a more or less broad yellow border. The variation 

 consists principally in the colour of the scutellum, and in the shape of the yellow band on 

 the fourth segment, which is sometimes of equal breadth, sometimes triangularly 

 expanded ; but in all my specimens the first three segments are black, clothed in the 

 male with a silvery, in the female with a golden, tomentum ; the extreme lateral end 

 of the posterior margin of the third segment shows a trace of yellow. In all these 

 specimens the wings are fulvous along the costa, as far as the origin of the second 

 vein ; beyond that the colouring is more brown, as far as the end of the third vein. This 

 agreement of specimens (Bellardi's and mine) coming from the same region, would 

 seem to prove that the geographical distribution of the varieties of this species is subject 

 to rule, and that they do not occur quite promiscuously. More detailed observations 

 on the subject would be interesting. 



I have before me a male and five females from Central America. 



2. Stratiomyia subalba. 



Stratiomyia subalba, Bellardi, Saggio &c. i. p. 31 \ 

 (?) Stratiomys subalba, Walker, List &c. v. p. 43 2 . 



Hab. Mexico, Tampico (de Saussure) \ Presidio (Forrer) ; Guatemala, San Geronimo 

 (Champion); Panama, Bugaba, Taboga Island (Champion).— Brazil, Para 2 . 



I cannot believe that this species is merely a variety of S. mutabilis ; besides the very 

 considerable difference in the colouring of the body and wings (the costal half of which 

 is uniformly brown), the abdomen is squarer and flatter than in the male of that insect. 

 Schiner, Reise d. Novara, Dipt., p. 61, speaks of varieties of S. mutabilis with the costal 

 half of the wings uniformly brown ; and Arribalzaga (Catalogue &c. p. 128) regards 

 S. subalba, Walk. (List &c. v. p. 43), as a mere variety of S. mutabilis. But is Schiner 

 right %, and is S. subalba, Arrib., the same as S. subalba, Bell. 1 Meanwhile I cannot 

 believe, until we have proof of the contrary, that the four male specimens before me are 

 ii mere variety of S. mutabilis. 



