~ 
Henry L. Bruner 
interna to include both the vena cardinalis and its physiological suc- 
cessor, the vena capitis lateralis. 
In adult Lacerta agilis the vena jugularis interna (v. j. 1., Text Fig. 2) 
arises from the posterior median portion of the sinus orbitalis, a great 
blood-space formed by the enlargement of certain veins of the orbit. 
The transition from the sinus orbitalis to the vein is a gradual one, for 
the vein itself is much enlarged for some distance behind the orbit. For 
descriptive purposes the sinus may be said to terminate at the optic 
chiasma, or more accurately, at the rostral margin of a cartilaginous 
plate, the subiculum infundibul of Gaupp, oo, which crosses the median 
line just behind the chiasma (8S. 7, Fig. 5, Plate I). At this point the 
sinus orbitalis shows a horizontal portion between the bursalis muscle 
and the oral mucous membrane, and a vertical portion which lies between 
the eye muscles and the muscles which fill the temporal fossa. The ver- 
tical part of the sinus reaches dorsad as far as the ramus frontalis 
ophthalmicus V. At the rostral margin of the subiculum infundibuli 
the ventral part of the sinus gives rise to the vena jugularis interna, 
while the vertical part is connected with a short vein, called by Grosser 
and Brezina “secondire Verbindung” of the vena cerebralis media 
(sees. 5. Plate-TsNext Hig. 2). 
From its origin the vena jugularis interna maintains a straight course 
toward the basisphenoid bone, which it meets lateral to the hypophysis. 
Throughout this stretch the vein is much flattened between the eye 
muscles and the adjacent parts, the main channel lying next to the middle 
line, while the lateral portion has an irregular and somewhat indefinite 
border (compare Figs. 4 and 5, Plate I). At the level of the posterior 
margin of the subiculum infundibuli the two ven jugulares are con- 
nected across the middle lne by a short anastomosis, which passes be- 
tween the floor of the cranium and the cartilaginous basis cranil, a 
median strip of cartilage formed by the fusion of the trabecul cranii. 
Behind this anastomosis the vena jugularis expands on the lateral aspect 
of the eye muscles and reaches the ramus ophthalmicus V. Just in front 
of the basisphenoid bone the lateral part of the vein receives from the 
foramen trigemini the vena cerebralis media secunda of Grosser and 
Brezina, (0.,c.. miss. Dext Wig. 2). 
At the rostral end of the basisphenoid bone the character of the vena 
jugularis interna is changed and the sinus-like vein, which has been 
hitherto practically a continuation of the sinus orbitalis, acquires a more 
definite wall and assumes the proportions of an ordinary vein. The re- 
duced vein, which is continuous with the median part of the enlarged 
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