232 REMARKABLE STRUCTURE IN 
I have therefore been very much interested by dis« 
covering (1875) in ants a structure which seems in 
some remarkable points to resemble that of the 
Orthoptera. As will be seen from a glance at Dr. 
Graber’s memoir, and the plates which accompany it, 
the large trachea of the leg in the Orthoptera is con- 
siderably swollen in the tibia, and sends off, shortly 
after entering the tibia, a branch which, after running 
for some time parallel to the principal trunk, joins it 
again. See, for instance, in his monograph, plate ii., 
fig. 43; plate vi., fig. 69; plate vii., fig. 77; &e. 
Now, I have observed that in many other insects the 
trachez of the tibia are dilated, and in several I have 
been able to detect a recurrent branch. The same is 
also the case in some mites. I will, however, reserve 
what I have to say on this subject, with reference to 
other insects, for another occasion, and will at present 
confine myself to the ants. If we examine the tibia, 
say of Lasius flavus, Fig. 9, we shall see that the 
trachea presents a remarkable arrangement, which at 
once reminds us of that which occurs in Gryllus and 
other Orthoptera. In the femur it has a diameter of 
about 5355 of an inch; as soon, however, as it enters 
the tibia, it swells to a diameter of about s1, of an 
inch, then contracts again to gt5, and then again, at 
the apical extremity of the tibia, once more expands 
to s35- Moreover, as in Gryllus, so also in Formica, a 
small branch rises from the upper sac, runs almost 
