266 BENJAMIN P. YounG 
slightly modified to pteropleurite (ptp?) and sternopleurite (stp?) as sug- 
gested by Crampton (1914 b) for anepimeron and katepisternum, respec- 
tively —seems advisable. Furthermore, Crampton’s term hypoepimeron 
(hem?) has been accepted on the same grounds. This leaves only the 
anepisternum to retain the more descriptive name, its anterior part 
being labeled “ aes,?’’ and its posterior part when present being referred 
to asi aes,7 ””. 
The generalized type of coxa as illustrated in Panorpa venosa (Plate 
XXXII, 76) —in which the pleural suture is continuous throughout the 
length of this first segment of the leg, dividing it into the true coxa (cx?) 
and the meron (me?), terms used by Walton (1900) — is to be recognized 
only in a few of the lowest families of flies, as the Tipulidae (Plate LX, 2 
and 3) and the Rhyphidae (Plate X, 4). In the last two figures evidence 
is given of the migration of the meron dorsad to become fused eventually 
with the lower pleural sclerite, the hypoepimeron. In all the higher 
families of flies this interpretation is placed on the fate of the meron, and 
the combined meron and hypoepimeron is termed, after Crampton (1914 b), 
the meropleurite (mep?). 
The basalare and subalare sclerites are often present in this order and 
are figured herein, although not labeled in most of the drawings. 
The sternum 
To the writer’s mind it seems doubtful whether the term sternopleurite 
should be used as its author intended, that is, to refer to a combined sternal 
and pleural sclerite, or rather to the part of the pleurite which borders on 
the sternum. The study of the venter of flies is carried on with difficulty 
because of the proximity of the bases of the legs. But a number of the 
broader representatives of the group show the same arrangement of sclerites 
as does Olfersia americana (Plate XX XII, 75), in which the two pleurites 
termed sternopleurites meet each other on the ventral side, apparently 
crowding out the anterior part of the sternum — the baszsternite (bs) of 
Crampton (1909). The fureasternite (fs) alone seems to remain in this 
eroup. 
The metathorax 
The tergum 
Compared with those of the mesothorax, all three plates of the meta- 
thorax are very small. As has been suggested, the large development of 
