356 Endocranium and Maxillary Suspensorium of the Bee. [ May, 
Burmeister attributes to Lepidoptera nothing more than a 
small bar across the occipital foramen. But we find (in the swal- 
low tail, Papilio turnus) a strong sub-quadrate frame arising in 
front of this foramen, and reaching forward so as to be fixed near 
the roots of the proboscis. 
That the mesocranial pillars represent involutions of the outer 
walls, may be understood from the trunk of the cray-fish, where 
(as Mr. Huxley has well shown) the ingrowths become plates or 
ridges, or even pillars. But we find a closer illustration in the 
heads of some other insects. Cicada has similar pillars with the 
bee, somewhat flattened out and attached to the sides of the head 
(the eyes here not reaching so far forward). This would indicate 
that in the bee the ridges have been displaced inwards by the 
encroaching of the eyes. (The clypeus of Cicada is transversely 
barred so as to show about ten pseudo-somites. It is easy to 
examine these parts from one of its exuviated shells.) 
The dragon-fly has a stout ridge below the occipital foramen, 
sending up processes to the clypeal region, as in the bee. But 
these processes are broadened out and transparent, and not rigid. 
The clypeus itself is soft and swollen, and has a deep transverse 
ridge to meet the processes. Thus the large, weak cranial wall 
is somewhat but slightly strengthened. 
The attempt to correlate the parts of the bee’s head with those 
of the head of the cockroach, gave rise to some interesting reve- 
lations. Here Huxley’s excellent description of the cockroach 
(“ Anatomy of the Invertebrated Animals ”) was in good season, 
but we soon found that his work was superficial and faulty on this 
part. He states that the endocranium of the cockroach “ extends 
as a cruciform partition from the inner face of the lateral walls of 
the cranium to the-sides of the occipital foramen ;” and speaks of 
the center of the cross as being “ pierced by a rounded aperture 
through which the cesophageal nerve-collars pass.” In fact, it is 
not cruciate in form, but consists of two pillars as in the bee (only 
softer), and united by membrane some way up, 2. ¢., crotch-webbe 
like the webbed fingers of a water-fowl. The upper band run- 
ning across is a fascia binding the two mandibles together (present 
in the bee, though not thus united with the mesocephalic rods). 
Thus we have a “tentorium,” or mesocephalic plate, forming 4 
thin diaphragm across the middle of the cranial cavity, with 
thickened borders in front and laterally, and itself concave up- 
