2 
Oo 
Henry L. Bruner 
A. THE VENA JUGULARIS INTERNA. 
The general arrangement of the cephalic veins of Emys europea much 
resembles that of Lacerta, though differing in some important particulars. 
The vena jugularis interna is a strong vein with definite walls, the an- 
terior part showing no marked enlargement. The vein begins at the 
caudo-median part of the sinus orbitalis and runs caudad, between the 
m. retractor oculi and the pterygoid bone, and on the median side of the 
processus parietalis pterygoidei. This part of the vein lies below the 
trigeminus nerve and corresponds to the vena cardinalis of Grosser and 
Brezina. The position of the vein is not intracranial, however, as stated 
by these authors, for the vein lies below the eye muscles, while the mem- 
braneous wall of the cranium lies above these muscles, the conditions 
being thus identical with those observed in the lizards (compare Figs. + 
and 5, Plate I, and Fig. 1, Plate I11). 
Caudal to the origin of the trigeminus nerve the vena jugularis interna 
runs under the tympanic cavity, passing below the auditory and above 
the post-auditory nerves. Excepting in the region of the trigemmus and 
auditory nerves the vein corresponds to the vena capitis lateralis of 
Grosser and Brezina. Under the posterior end of the parotic process the 
vena jugularis interna receives the vena cerebralis posterior, then bends 
laterad to meet the vena mandibularis. Beyond its junction with the 
latter, the vena jugularis interna runs close to the skin and represents a 
vena jugularis externa (Rathke, 48). 
The most important tributaries of the vena jugularis interna of Emys 
are the following: 
a. THE SINUS ORBITALIS. 
This sinus is well developed in Emys, resembling in its distribution 
the sinus orbitalis of the lizard. In the turtle the sinus is bounded di- 
rectly by the smooth muscle of the orbit, m. compressor sinus orbitalis, 
which shows a very strong development (compare page 96). The m. 
depressor palpebre inferioris is wanting. The sinus orbitalis receives 
practically all of the blood from the anterior head region and palate, the 
chief tributaries being the following: 
(1) Vena Frontalis—This vein drains the region of the frontal bone 
and discharges into the anterior part of the sinus orbitalis. 
(2) Sinus Palatinus—This sinus is a system of enlarged vessels, 
which lie close to the oral mucous membrane. It includes (a) a sinus 
*Gaupp, oo, D. 548, has pointed out this error. 
