38 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The vestiture of the thorax is of some interest. In Ravinia, the 
metanotum is always clothed with short bristles; in the three species 
of Boettcheria, with short hairs. The scutellar bridge (juxtascutel- 
lum), which is only fully exposed when the wings are spread, often 
bears a group or tuft of hairs, that in Ravinia are always short, but 
long in some species of Sarcophaga. The side of the thorax is clothed 
with hair, which is unevenly distributed, leaving some parts bare and 
affording no features of value. The color of the hairs covering the 
spiracles is given in all descriptions. Possibly this is not of great value, 
but is sometimes useful. Sarcophaga haemorrhoidalis Meigen normally 
lacks prescutellar acrostichal bristles, but when these are present as 
they not uncommonly are, the dark color of the hairs covering the 
anterior spiracle is of assistance in separating it from S. falculata 
Pandelle. In all small species of Ravinia which have been examined 
the hairs of the anterior spiracle are grayish though in R. communis 
they may be slightly tinged with brown at the base ; also the posterior 
spiracular cover is always pale yellowish. Similarly in the assidua 
group (Sarcophaga) the relation of color holds good for all species. 
The epaulets are important. The characters they furnish are color 
distinctions but I have never found any instances of radical variation. 
In all species of Ravinia they are either brown or light yellow or only 
yellowish, in all species of Boettcheria at present known they are brown 
(see generic description), while in Sarcophaga they vary from brown 
and light yellow to brown or black ("dark" of descriptions). In 
Sarcophaga fidvipes Macquart they are brown and light yellow, but 
brownish black in its northern subspecies nigra. On the inner margin 
there are usually two slender bristle-like hairs, but in Sarcophaga 
scoparia Pandelle three often occur, while I have never noted more 
than one in Wohlfartia. 
The wings furnish but few good characters. The angle formed by 
the bend of the fourth vein is reasonably constant and sometimes 
useful. The various curves and convolutions of the posterior cross- 
vein have been used by several writers but this vein is probably subject 
to as much variation as any character presented. Both the third and 
the first veins may be bristly on their basal portion. Bottcher con- 
siders that this character of the first vein is inclined to vary, but I 
have never kno\\Ti these bristles to be absent in any of our American 
species in which they are normally present though the distances to 
which they may extend along the vein vary. The costal spine may 
