524 How Cockroaches and Earwigs fold their Wings. [ September, 
It may here be worth while, by the aid of diagrams, to explain 
a little more carefully the mode in which the wings are folded. 
Figure 32 may represent a fully expanded wing, such as that last 
a described ; ab, a'b' (p of Figure 
29) may be called the principal 
part of the wing, and r the di- 
verging field ; the bent longitu- 
dinal line, separating the ante- 
rior zone (aa!) from the reversi- 
Fia. 82, ee ble zone (66') is the principal 
longitudinal fold of the wing, to which we have constantly re- 
ferred ; the straight line separating the basal (veined) portion of 
the wing (ad) from the apical (coriaceous) reflectible portion 
(a'b') is the transverse fold, which in the simpler wings is repre- 
sented by the upper and lower margins of the apical triangle. 
The diverging field (7) first folds like a fan, so that 6 and r 
together are no broader than a ; the wing then folds longitudi- 
nally, bb! bending downward beneath aa’, and presents the ap- 
pearance seen in Figure 33, where a and a! are alone visible; a' 
now bends upward and folds back 
upon a,as in Figure 34, and the 
E] F wing is reduced to a little pad» 
-— which scarcely surpasses the basal 
portion of the anterior zone 4. 
7 Fie. 33. Figures 35 to 37, which represent 
a theoretical section of the wing along the line xg (Figure 33), will 
explain still further this mode of duplicature. @ z s 
In Figure 35 the wing is fully expanded, and e¢ ; 
represents the costal, z the posterior border of Fra. 34. 
the wing; a, b and r represent the same part as in Figure 32, p 
Inman G4 p_e > the longitudinal fold or plication 
Fig. 35. separating the anterior from the re- 
versible zone, and g the point of division between the reversible 
zone and the diverging field. In Figure 36 the first step ear 
SAMI, the result of the plication along the lon- 2an 1 
gitudinal fold p ; Figure 37 (in which the letters ro 
bearing primes represent the same parts in the Fic. 
a30 
reflectible portion as the equivalent letters in the basal portion 
of the wing) carries the process to its completion. Figure 88 
represents a horizontal section of the completely folded wing a 
18 the anterior, o! the posterior articulation of the wing; 0! % T° 
Presents the diverging field, o’ #' the basal portion and # é the 
