The Anatomy of Ants. By Sir John Lubboclt, Bart. 135 
nothing corresponding to them occurs in any other insects, or 
indeed in any other Arthropods. 
I have therefore been very much interested by discovering 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 is considerably 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 ; &c. 
Now, I have observed that in many other insects the tracheae 
of the tibia are dilated, sometimes with a recurrent branch. The 
same is the case even 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, we shall see that 
the trachea presents a remarkable arrangement (Plate CXCII., Fig. 
5), which at once reminds us of that which occurs in Gfryllus and 
other Orthoptera. In the femur it has a diameter of about 
of an inch ; as soon, however, as it enters the tibia, it swells to a 
diameter of about of an inch, then contracts again to and 
then again, at the apical extremity of the tibia, once more expands 
to jJ-q. Moreover, as in Gfryllus, so also in Formica, a small branch 
rises from the upper sac, runs almost straight down the tibia, and 
falls again into the main trachea just above the lower sac. 
The remarkable sacs (Plate CXCII., Fig. 5 , ss ) at the two 
extremities of the trachea in the tibia, may also be well seen in other 
transparent species, such, for instance, as Myrmica ruginodis and 
Pheidole megacephala. 
At the place where the upper tracheal sac contracts (Plate 
CXCII., Fig. 5 ), there is, moreover, a conical striated organ ( x ), 
which is situated at the back of the leg, just at the apical end of 
the upper tracheal sac. The broad base lies against the external 
wall of the leg, and the fibres converge inwards. In some cases 
I thought I could perceive indications of bright rods, but I was 
never able to make them out very clearly. This also reminds us 
of a curious structure which is found in the tibiae of Locustidae, 
between the trachea, the nerve, and the outer wall, and which is 
well shown in some of Dr. Graber’s figures. 
Although I am not yet able to give anything like a complete or 
satisfactory account of the structure of the head, partly in conse- 
quence of its minuteness and partly of its complexity, still I hope 
to be able to bring before you some points of interest. Meinert’s 
admirable memoir, “ Bidrag til de Danske Myrers Naturhistorie,”* 
* ‘ Danske Vid. Selskabs Skr.,’ 1861. 
VOL. XVIII. 
L 
