Henry L. Bruner 39 
by the vena cerebralis posterior in Emys resembles the temporary ring 
observed by Grosser and Brezina in their Lacerta embryo, series XIV, 
head 4.1 mm. 
d. VENA MANDIBULARIS. 
This vein has not been fully worked out. Its posterior part lies lateral 
to the mandible, where it receives a small vein from the side of the head. 
The vena mandibularis discharges into the posterior end of the vena 
jugularis interna, near the junction of the latter with the vena jugularis 
externa. 
IV. GENERAL REMARKS AND SUMMARY ON THE CEPHALIC 
VEINS OF THE SAURIA, OPHIDIA, AND TESTUDINATA. 
1. In Lacerta and Emys practically all of the blood of the anterior 
part of the head is discharged into the sinus orbitalis, which includes 
among its tributaries the vena maxillaris (vy. maxillaris superior of 
authors). In Tropidonotus the blood of the anterior region of the head 
passes partly into the sinus orbitalis, partly into the vena maxillaris 
which has direct connection with the vena mandibularis behind the orbit. 
2. In Lacerta and Emys the sinus orbitalis is drained only by the. 
vena jugularis interna. In Tropidonotus the vena jugularis interna 
arises from the sinus orbitalis but the anterior part of the vein is small 
and carries little blood from the anterior part of the head. The chief 
outlet of the sinus orbitalis of the snake is the vena maxillaris. 
3. In all of the forms studied, lizard, snake, and turtle, the vena jugu- 
laris interna eventually receives the greater part of the blood from the 
head. In the lizard, under ordinary conditions, the vein probably car- 
ries nine-tenths of all the blood from the face and cranium, the re- 
mainder passing through the vena jugularis externa, vena spinalis, and 
smaller vessels. 
4. The veins of the brain undergo little modification with the approach 
of adult life. In Tropidonotus and Emys the ventral end-piece of the 
vena cerebralis anterior and the secondary connection of the vena cere- 
bralis media form a continuous vein which runs from the sinus orbitalis 
to the vena cerebralis media. In the snake this vein is intracranial; in 
the turtle it is extracranial. In Lacerta a similar extracranial vein 
occurs but it is much reduced, owing to the posterior extension of the 
sinus orbitalis; it has little importance in the adult lizard. 
The vena cerebralis media of Tropidonotus shows the following anasto- 
moses: (a) With the vena jugularis interna, through the vena capitis 
