224 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
a little more than half the length of the tegmina, though in some 
locusts it is lacking. The second and longer vein, also undivided, 
is the 'mediastinal' (m). The third and much larger vein is the 
'humeral' (h), sometimes called the 'sub-costal.' It gives rise to 
several large branches, the subdivisions of which form the frame- 
work of the greater part of the wing-cover. The larger of these 
branches (d) is known as the 'discoidal vein,' its branches being 
designated as {d', d"), etc. The fourth or 'median vein' (w) is 
much smaller and soon divides into branches of nearly equal 
size. Above or behind the median vein is sometimes present a 
short, undivided vein (i), known as the 'intercalary vein.' Next 
in order is the 'ulnar vein' {u), which gives off several branches 
(w'j u", etc.). The upper division of this vein (o) is known as 
the 'posterior ulnar' or the 'sub-median vein.' Close to and 
parallel with it near the upper or hind margin of the wing-cover 
is the undivided 'anal vein' (a) ; while the uppermost vein of the 
wing-cover, also undivided, is the 'axillary vein' {x). 
"The tegmina are divided by these veins into three areas: the 
'costal' or 'marginal area' (M) forms the lower or front edge of 
the wing-cover and is bounded above and behind by the humeral 
vein. The 'median' or 'discoidal area' (D) is much the largest 
and lies between the humeral and posterior ulnar veins. The 
'anal' or 'dorsal area' (X) is the free margin lying along the back 
above and behind the anal vein" (Blatchley). 
The venation of the tegmina and wings varies characteristically 
in different families, genera, and sometimes even species of 
Orthoptera, though showing the same fundamental plan. The 
names applied to the veins differ widely and the student is 
referred for fuller information to the works on special families 
or lesser groups. Diagrams of the venation of Gryllidae and Blat- 
tidae are given in this Manual under the headings of those families. 
Abdomen. 
This (Figs. 16, 17) is elongate, tapering posteriorly, and plainly 
shows in its middle portion the successive segments of which it is 
made up, as previously described. The tergum of the first segment 
is widely separated by the bases of the hind legs from its corre- 
sponding sternum, which consists of a broad transverse plate 
extending between the hind legs and having an anterior lobe 
