162 D1PTERA. 



being granulate along the costa. Fclimus Mrtus, Loew, Deutsche ent. Zeit. 1876, 

 p. 209 (Acarnania), with its opaque black colour and its golden pubescence, seems to 

 be nearer to E. auripilus than the other two species described by Loew. 



Fam. THEREVIDJE. 



The small number of specimens before me belonging to this family represent about 

 half a dozen species, collected at Presidio, Mexico (Forrer), and in Northern Sonora 

 (Morrison). I cannot determine any of these from the existing descriptions, although 

 most of them reproduce very closely the well-known types of North-American "Therevse," 

 and especially "Psilocephake." Many descriptions of Therevidse are based on single 

 specimens, while the species are not quite constant in their coloration, especially in 

 that of their wings. I have, for instance, a Psilocephala, from Sonora, represented by 

 seven female specimens, which comes very near to P. platancala, Loew, and also to the 

 South-American P. stigmaticalis, Schin., but I cannot identify it with either, although 

 it may be one of them. I will therefore describe one species only, which, although 

 represented by a single specimen, is sufficiently characteristic. 



THEREVA. 



Thereva, Latreille, Precis des Car. gen. des ins. p. 167 (1796). 



l. Thereva Mbocera, sp. n., $ . 



Antenna; with an onion-shaped third joint; front with a pair of velvety-black spots; body pale brownish- 



ochraceous ; wings densely variegated with brown spots. 

 Length 11 millim. 



Hob. Mexico, Presidio (Forrer). 



Antenna? : first joint short, cylindrical ; second joint small, rounded ; third joint onion- 

 shaped, but flattened from the sides, its base coarctate as usual in Thereva (but more 

 distinctly), its apical part showing an elongation nearly as long as the incrassate portion 

 of the joint and divided about the middle by a distinct segmentation ; in colour pale 

 brownish-yellow, more brown on the incrassation, nearly black at the tip. Palpi club- 

 shaped, brownish-yellow. Face and front fawn-coloured (cervinus), sericeous ; the front 

 flat, with a velvety -black, round spot on each side near the eye ; occiput greyish-pollinose, 

 more yellowish above, beset with black bristles. Thorax brownish-ochraceous, greyish- 

 pollinose on the pleurae; macrocheetee black. Abdomen brownish-ochraceous, beset 

 with short, black, erect pile, especially towards the end; female ovipositor with a 

 coronet of black spines. Legs brownish-yellow, the tarsi darker brownish towards 

 the end (the front pair is broken off). Wings densely variegated with brown spots and 

 dots ; subcostal cell brownish-yellow ; stigma brown ; a series of brown dots along the 

 second vein ; more or less distinct brown clouds along the other veins (they are longer 



