92 
ZOOLOGICAL EXERCISES, 
to meet the cubital vein. Below the discoidal comes 
the postical vern, which is joined to the discoidal by 
a sinuated transverse vein, nearer the margin than 
the centre of the wing. Below the postical is a short 
vein, the anal vein, which does not reach the margin. 
Near the base of the wing is the posterior transverse 
vein, crossing the postical vein, and uniting the anal 
with the discoidal vein. The two small cells thus 
enclosed are the posterior basal cells, and the cell 
enclosed by the basal portions of the cubital and 
discoidal veins, and the transverse vein, is the an- 
terior basal cell. The other cells are named from the 
veins enclosing them. The mediastinal cell is be- 
tween the mediastinal and costal veins; it is 
divided into two parts by a transverse vein. The 
space enclosed between the mediastinal and sub-costal 
veins is the costal cell. That between the sub-costal 
and radial veins isthe swb-costal cell. That between the 
cubital and radial veins is the cubital cell. The jirst 
posterior cell is enclosed between the discoidal and 
cubital veins, the transverse vein, and the margin of 
the wing. The second posterior cell extends along 
the margin of the wing from the discoidal to the 
postical vein, and is bounded internally by the 
sinuous transverse vein, which may be looked upon 
as a branch of the postical. Between the second 
posterior cell and the first posterior basal cell lies the 
discoidal cell. The anal cell lies between the postical 
and anal veins; it is not complete, as the anal vein. 
does not reach the margin. The small appendage at 
the posterior base of the wing is the alulet. The 
student should make a drawing of the wing, and 
write the names of the veins and cells on it. 
