298 EDWARD PHELPS ALLIS, JR. 
fissura orbitalis superior of man plus the foramina rotundum 
and opticum. In the Macrochiroptera the artery traverses a 
canalis pterygoideus in the basis cranii of this region (Grosser), 
while in Rhinolopas it lies, asin man, wholly free along the lat- 
eral wall of the cranium. ‘This is, then, wholly in accord with 
the varying relations of this artery to the lateral wall of the cra- 
nium in fishes, the artery traversing the pars jugularis of the 
trigemino-facialis chamber in all of the Teleostei in which that 
part of the chamber occurs, traversing a foramen in its lateral 
wall in Amia, entering it with the nervus palatinus facialis in 
Lepidosteus, and lying wholly external to the lateral wall of the 
cranium in those fishes (Cottus, Amiurus) in which the pars jugu- 
laris of the trigemino-facialis chamber is not enclosed. It is 
thus evident that, both in the dog and in the Macrochiroptera, 
the processus pterygoideus has fused with the lamina ascendens 
of the ala temporalis and so has enclosed the external carotid in 
a canal which corresponds to a part of the pars jugularis of a 
trigemino-facialis chamber, and that, in Vespertilio, the mesial 
wall of this canal has been resorbed, the artery then lying in a 
part of a trigemino-facialis chamber. 
The fovea epitympanica of rabbit embryos is a depression on 
the lateral surface of the chondrocranium, said by Voit (’09, p. 
450) to lie between the crista facialis and the tegmen tympani. 
The tegmen tympani is said to arch over the upper edge of the 
fovea, and it is so shown in his figures, the tegmen apparently 
forming the dorsal portion of the lateral wall to the fovea. It is, 
however, said (I. c., p. 449) that the tegmen is perforated by the 
foramen faciale externum s. secundarium, but as that foramen 
~ lies in the plane of the mesial wall of the fovea epitympanica, 
it would seem as if there must be some error in the descriptions. 
But however this may be, the fovea lodges the upper ends of the 
malleus and incus, and these two cartilages lie external to the 
nervus facialis, to the posttrigeminus portion of the vena capi- 
tis lateralis, and to the arteria stapedialis (maxillaris interna, 
carotis externa). The fovea and the space traversed by this 
nerve, vein, and artery thus together form a cavity which has 
the relations to the cranial wall of the pars jugularis of a tri- 
