18 The Cephahc Veins and Sinuses of Reptiles 
tudinalis cerebri under the crista sagittalis of the superior occipital bone. 
From its origin the vein runs laterad until it reaches the prominentia 
vestibularis interna, on whose dorsal aspect it runs forward to the fora- 
men trigemini (incisura prootica of Gaupp, 00). Here the vein forms 
a sinus prooticus, which surrounds the ganglion of the maxillary and 
mandibular branches of the trigeminus, excepting in a dorsal direction, 
where the ganglion lies in contact with the prootic bone. Laterally the 
sinus is bounded by the m. temporalis, between which and the m. ptery- 
goideus internus the sinus extends as far as the pterygoid bone. 
From the rostral part of the sinus prooticus an extracranial vein, the 
vena cerebralis media secunda (v. ¢. m. s., Text Fig. 2), runs ventrad and 
enters the vena jugularis interna just in front of the basisphenoid bone. 
In one of the adult specimens examined during the preparation of this 
paper the posterior outlet of the vena cerebralis media also persists as a 
small vein (v. c. m., Text Fig. 2), although it is probably obliterated as 
a rule. 
_ The vena cerebralis media secunda is connected with the sinus orbitalis 
by a small vein which runs along the ventral aspect of the ramus ophthal- 
micus V. It is the secondary connection (secundire Verbindung) which 
is described on page 16. In the adult lizard this vein is of little 
importance and it may be doubted if it carries blood to the sinus orbitalis 
under ordinary conditions. 
The sinus prooticus also receives several small veins from the m. 
temporalis, the most important of which begins near the articulation of 
the jaw and runs dorsad on the lateral aspect of the pterygoid bone. In 
an embryo Lacerta with head 5.2 mm. long this vein is connected with the 
vena mandibularis interna. The same relation has also been observed 
in advanced embryos of Cnemidophorus. 
The most important tributaries of the vena cerebralis media are the 
vena capitis dorsalis and vena hypophyseos. 
1. VENA CAPITIS DORSALIS (v. c. d., Text Fig. 2).—The vena capitis 
dorsalis drains the muscles of the occipital fossa, including the cephalic 
portions of the mm. capiti-cervicales and the posterior dorsal portion of 
the m. temporalis. The vein is formed by the union of two roots, a 
lateral one which arises above the parotic process, and a median one which 
has its origin above the lateral margin of the foramen magnum. ‘These 
two veins run forward under the m. capiti-cervicalis superior and unite 
below the posterior margin of the parietal bone, directly lateral to the 
crista sagittalis of the supraoccipital. The sinus-like trunk vein con- 
tinues forward a short distance, then bends toward the median line and 
