THE HABITS AND STRUCTURE OF MOTHS. 
XXV 
nervures, is called the discoidal cell; it is sometimes divided 
into anterior, middle, and posterior discoidal cells. In 
some genera the transverse nervule is wantiDg between 
nervnles 4 and 5, so that the discoidal cell is open, and con¬ 
tinuous with cell 4. There are also often small closed cells 
upon the discoidal cell, called accessory cells. Sometimes 
these are at the base of the hind wings in front, or when the 
discoidal cell is divided, they are placed externally between 
the two divisions, on account of the bisecting nervure forking 
on the basal side. In other cases they are placed, on the 
fore wings, at the anterior angle of the discoidal cell, where 
they are formed by the junction or crossing of two nervures, 
but generally through one branch sending off a nervule to 
the next. Cells thus formed are called appendicular cells. 
In the Tineae with lanceolate hind wings, the arrange¬ 
ment of the nervures is simplified. The 
discoidal cell becomes less distinct or 
completely disappears, as all the ner¬ 
vures arise from the base, or from other 
nervures. The number of nervures is 
also reduced in these moths, especially 
in the hind wings. 
The surface of the wings is divided 
longitudinally into three areas: basal, 
central, and marginal. In many genera these areas are 
marked on the fore wings with simple, double, or multiple 
transverse lines, which are often filled in or bordered with 
lighter, and are called the anterior and posterior trans¬ 
verse lines, or simply the first and second transverse lines. 
These are most typically present in many of the Noctuse, 
and form part of what is called the Noctua-pattern. The 
posterior transverse line is by some authors called the 
elbowed line. There is also frequently a short line on 
the costa, nearer the base, which does not reach the inner 
margin, and is called the half line. Besides this there 
is another line towards the hind margin, known as the 
submarginal line. Resting on the inner side of the sub¬ 
marginal line, we often find several black sagittate spots, 
pointing towards the base. There are also three marks, called 
stigmata, forming part of the Noctua-pattern. One of these, 
usually hollow, is situated on the anterior transverse line, in 
cell lb, and is called the claviform stigma; a smaller one, 
usually round, is placed in the discoidal cell, and is called the 
orbicular stigma; the third, which is situated behind the 
orbicular, is larger, elongated, and rests upon the transverse 
nervule; from its usual shape this is called the reniform 
Fig. 3. 
