MYODOME AND TRIGEMINO-FACIALIS CHAMBER 293 
ently also in different species of the Mammalia, this giving rise 
to a vena jJugularis interna which issues, either through a fora- 
men jugulare spurium or a foramen jugulare, or even through 
both those foramina; these two connections with the primitive 
vein thus evidently corresponding to those referred to above 
in the Teleostei. The sinus cavernosus is said by Salzer (I. ¢, 
p. 252) to be formed from the veins which primarily collected 
the blood from the eyeball and the orbit, and which acquire 
a secondary connection with the sinus petrosus. This secondary 
connection must certainly be formed by a vein, the homologue 
of the pituitary vein of fishes, which has become important be- 
cause of the abortion of the short vertical venous commissure 
which primarily connected the venae capites media and later- 
alis between the trigeminus and facialis ganglia. I do not find 
that Salzer mentions the abortion of this connection, but his 
figures show that it is absent in older embryos. Thus the sinus 
cavernosus of mammals is the pituitary vein of fishes, and it 
is said by Salzer (1. c., p. 242) primarily to have delivered the 
blood from the orbital veins into the sinus petrosus. Later, 
the flow of blood is reversed, in the porpoise, and the sinus 
cavernosus and the orbital veins are drained by the facial vein, 
the flow of the blood in the sinus cavernosus thus now being 
in the same direction as in the pituitary vein of fishes. 
The sinus cavernosus of mammals thus certainly contains 
no part of the primitive vena jugularis, but a persisting portion 
of that vein forms the connection between it and the orbital 
veins. In the Sauria the sinus cavernosus is said by Grosser 
and Brezina (’95, p. 323) to be perhaps a remnant of the vena 
cardinalis anterior, and there to be extracranial in position (I. 
¢., p. 321); neither of which statements is correct, for the con- 
ditions are here certainly as in the Mammalia. Gaupp (’00, 
p. 548) quotes Grosser and Brezina as here saying that the 
sinus cavernosus is actually (wohl) a part of the vena cardinalis, 
and adds that he has himself confirmed this, as well as its 
extracranial position, in embryos of Chelone. 
These statements regarding this sinus led me formerly to 
conclude (Allis, ’09, p. 193) that the venous vessel which tra- 
