562 THE AMERICAN NATURALIST. [VoL. XXXII. 
wings of many other insects (Heteroptera, certain Blattidz, 
et al.); and it probably would not have been seriously urged but 
for the presence of the so-called rudimentary wings beneath the 
elytra of certain beetles. 
When, however, the supposed rudimentary wings are exam- 
ined, they are found to correspond in structure and position to 
the alulz of the wings of other insects. The most conclusive 
evidence of this correspondence is the fact that they are 
margined by the cord-like structure which has been termed the 
Fic. 50. — The tracheation of the wings of a cerambycid pupa. 
spring-vein. This arises from the caudal border of the scutel- 
lum, and is a distinctive characteristic of this portion of the 
wing. The presence of these membranes beneath the elytra, 
therefore, merely indicates that if the elytra are modified wings 
they do not correspond to entire wings but to wings minus the 
alulze. 
When the elytra of a pupa of a beetle are examined, they ar 
found to be traversed by several, usually five or six, longitudi- 
nal tracheæ. Although these tracheze may give rise to a greater 
or less number of smaller trachee, there is nothing in the 
branching of them, in any of the forms that have as yet fallen 
under our observation, that corresponds with the branching of 
the trachez in our hypothetical type. But as this is almost as 
true of the hind wings, it has little bearing on the question of 
