292 EDWARD PHELPS ALLIS, JR. 
is connected with an intracranial vein, the encephalic vein of 
Allen (05), which enters the trigemino-facialis recess, perforates 
its lateral wall posterior to the nervus trigeminus, and falls 
into the vena jugularis. In other Teleostei the pituitary vein is 
connected with intracranial veins which issue through the fora- 
men vagum there to fall into the vena jugularis. If either of 
these two connections were to become important, the flow of 
blood in the pituitary vein would be reversed, and a vein would 
be formed whieh would drain the hypophysial region and would 
issue, in the one case, through a foramen jugulare spurium, and, 
in the other, through a foramen jugulare. 
In the Amphibia and Reptilia the vena jugularis always passes 
mesial to the ascending process of the palatoquadrate, or its 
homologue, the antipterygoid, and then, in each case, traverses 
the pars jugularis of the trigemino-facialis chamber, never there 
traversing any portion of the lateral wall of the neurocranium. 
The arteria carotis externa of fishes, like the vena jugularis, 
always traverses the pars jugularis of the trigemino-facialis 
chamber, when that part of the chamber has been separated 
from the pars ganglionaris, never traversing the pars ganglio- 
naris. On issuing from the chamber into the orbit, it always runs 
outward, posterior and lateral to the pedicel of the alisphenoid. 
In the Amphibia and Reptilia it traverses the pars jugularis of 
the trigemino-facialis chamber, always lying lateral to the 
lateral wall of the neurocranium, and issues from the chamber, 
posterior to the ascending process of the palatoquadrate in the 
Amphibia, or to the antipterygoid in the Reptilia, thus lying 
lateral to that element of the cranial wall. 
In embryos of the porpoise the vena jugularis of fishes is rep- 
resented in the vena capitis media plus the vena capitis lateralis, 
and, as described by Salzer (’95), all the cerebral veins empty 
into it, some anterior, some posterior to the nervus trigeminus, 
between it and the nervus facialis, and some in the region of the 
nervus vagus. The anterior of these three connections with 
the primitive vena jugularis loses its importance in later stages 
of development, the other two increasing, but varying in rela- 
tive importance at different stages of development, and appar- 
