DIPTERA. 317 
I have often found numbers of the . arcuatus on the dust of old 
walls(1). 
Those species, in which the first cells of the posterior edge of the 
wings are entirely open and longitudinal, composed, in the work of 
Meigen, two other genera: 
Homatura, where the abdomen presents five segments, and Ac- 
ToRA, where it exhibits six. The head is still more compressed 
than in the preceding subgenera. The seta, according to him, is 
naked, but I have seen it plumous in some specimens(2). 
There, the antenne are almost contiguous; the cells of the poste- 
rior edge of the wings are always open. 
Those Gymnomyzides in which the antenne are very short, and 
inserted, as in the last subgenus, under a sort of arch and near the 
middle of the face, form the genus Gymnomyza of Fallen(3). Those 
in which these organs are inserted higher up, without any distinct 
appearance of an arch at their origin, and that terminate in an elon- 
gated palette, compose the genus Loncnza of Fallen and Meigen. 
According to the latter the front is narrower in the males than in 
the females, and we see by their character that these Insects are 
connected in some respects with various species of Anthomyzz(4). 
The antennz of the Celyphi and Lauxaniz are also inserted higher 
than in the other Gymnomyzz. 
Our second section of the Muscides, which will form our ninth 
and last sub-tribe or general division, that of the Hyrocrra, com- 
prises but a single subgenus, very distinct from the preceding ones 
in several characters. The palpi are always exterior; the antennz 
inserted near the oral cavity are very short, and terminated bya 
thick and almost globular joint, with a very long seta. The wings, 
whose edge is densely ciliate superiorly, present near the base a 
stout oblique nervure, which extends to the margin where this stigma 
is placed in the Hymenoptera, and from this nervure proceed three 
others which run almost parallel with each other, in a longitudinal 
direction; hence the origin of the name 7vrineura, given to this sub- 
genus by M. Meigen. The body is arcuated, the legs stout and spi- 
nous, and their thighs large and compressed, the posterior ones par- 
ticularly. These Insects are extremely vivacious, and form in our 
‘* Genera” the genus 
Puora, Lat.—7vrineura, Meig. 
(1) See Lat., Gen. Crust. et Insect, IV, 357; Meig., and Fallen. 
(2) See Meigen. 
(3) Fallen, Dipt. 
(4) Fall. and Meigen. 
