96 DIPTEEA. 



visible. The brown abdomen densely clothed with rufous appressed scale-like hairs concealing the 

 ground-colour ; in the middle of each segment a row of long erect, black hairs is visible (some specimens 

 show traces of transverse rows of yellowish-white hairs) ; the sides have a fringe of rufous hairs, longer 

 towards the base, and within which, on segments 2-5, tufts of black hair are visible ; venter with rufous 

 hair. Legs rufous, the tips of the tarsi black ; bristles black; femora and tibise covered with scales, which 

 in a certain light appear yellowish. The brown portion of the wings variegated with yellowish-brown, 

 ill-defined spots, especially on the humeral and the other cross-veins, near the origin of the second vein, 

 at the distal end of the second basal cell, &c. ; the origin of the third vein is covered by a dark brown spot, 

 on both sides of which, within the marginal and submarginal cells, there are lighter shades of brownish ; 

 the hyaline spots are as follows — a small double one across the anal and axillary cells, a large triangle on 

 the posterior margin (the apex of which crosses the discal cell, but does not reach beyond it), a spot across 

 the distal portion of the inner submarginal cell varying in size and sometimes disappearing altogether ; 

 the brown pattern of the apex of the wing is very variable — generally, the brown fills out the distal end 

 of the marginal cell, except an irregular hyaline spot across it, between the tips of the first vein and the 

 second ; the second submarginal cell is likewise brown, with a hyaline space on its distal side; but in some 

 cases the hyaline space of the marginal cell communicates across the second submarginal with the hyaline 

 of the posterior side of the wing (the figure represents this variety) ; adventitious spots sometimes occur — 

 for instance, in one specimen there is a double spot at the end of the first posterior cell. 

 Length 8-12 millim. 



Eab. Mexico, Northern Sonora (Morrison). 



Twenty specimens of both sexes. 



N.B.— Anthrax laeera, Wiedem. Auss. zweifl. Ins. ii. p. 634 (Mexico ; Berlin Mus.), 

 is very like S. clelia, but a distinct species ; the difference in the coloration of the 

 abdomen is especially striking. 



1SOPENTHES, gen. nov. 



Three submarginal cells ; third joint of the antennae short, onion-shaped, with a very long style, not bisected 

 by a suture ; no tooth at the base of the ungues; distinct, although very small, pulvilli ; proboscis short, 

 retractile, with fleshy lips. Legs delicate ; front legs beset with spinules ; joints of the front tarsi distinctly 

 marked ; front ungues not unusually small. 



The two species described below show, in their structure and colouring, a most 

 remarkable resemblance to the genus Eemipenthes, Loew, which I have included in the 

 group Anthrax, sensu stricto ; the presence of three submarginal cells seems to be the 

 only difference. (Compare this group.) 



1. Isopenthes blanchardiana, e ? . 



Exoprosopa blanchardiana, Jaennicke, Neue exot. Dipt. p. 33, t. 2. f. 20 \ 



Body black, with some yellowish pile on each side ; wings dark brown, except the margin between the apex and 



the fourth posterior cell, only the end of the first posterior cell (about one fifth of its length) remains 



hyaline. 

 Length 8-10 millim. 



Eab. Mexico \ Northern Sonora (Morrison), Oaxaca (coll. Bellardi). 



Five specimens ( s 2 ) from Northern Sonora enable me to complete the description 

 of the body, which Jaennicke drew from abraded specimens. The prevailing colour 

 of the body is black ; the usual collar in front, as well as the long hair on the 



