344 INSECTA. 
The posterior thighs are stout, and dentated or spinous on the inner 
side. The Tarsi have but two pellets. The posterior cells of the 
wings are complete or closed before the margin, and narrow or elon- 
gated, oblique or transverse. 
These Insects compose the genus 
Mypas, 
Which is divided into two subgenera. 
Crpua.ocera, Lat., 
Where the proboscis is in the form of a long and projecting siphon *. 
Mypas, Fab., 
Or Mydas proper, where that or an, as is usual in this family, ter- 
minates by two large lips f. 
In the others, the antenne are scarcely longer than the head, cylin- 
drical, and tapering to a point at their extremity. The tarsi are 
furnished with three pellets. The posterior cells of the wings are 
longitudinal and closed by their posterior margin. 
Curromyza, Wred., 
Where the antennz are composed of five well separated joints, the 
two last of which are the smallest f. 
Pacuystomes, Lat., 
Where the antennz are composed of three joints the last of which is 
divided into as many rings §. 
In the second section, that of the Decatoma, Lat., we find antennze 
always composed of three joints, the last of which, the longest, with- 
out stilet or seta, and divided into eight rings, is clavate in some, 
and almost cylindrical or in the form of an elongated cone in the 
others. The wings are usually incumbent on the body. The tarsi 
are furnished with three pellets. 
These Insects may be united in one generic section. 
XYLOPHAGUS. 
In some, the antenne are much longer than the head, with the two 
first joints very short and the third very long, compressed, forming 
* A subgenus established on an Insect from the Cape. 
t+ See Fab., Lat., and particularly Dalm., Dipt. Exot., 115, who describes séve- 
ral species. ‘This subgenus and the preceding one appear to form a particular divi- 
sion, which, in a natural order, should perhaps be placed higher. The wings have 
some afiinity with those of the Pangonie. 
t Wied., Dipt.. Exot., I, viii. 
§ Lat., Gener. Crust. et Insect., IV, 286; Encyc. Méthod., article Pachystome. 
The larva of the P. syrphoide; Panz., Faun. Insect. Germ., Ixxvii, 9, the female; 
lives under the bark of the Pine; its pupa resembles that of a Tabanus. 
