34 The Cephalic Veins and Sinuses of Reptiles 
rostrum the two vene maxillares communicate across the middle line 
of the head, the connection occurring just behind the alveolar portion 
of the intermaxillary bones, where the veins lie next to the oral mucous 
membrane. Behind this point the two veins separate a short distance 
and pass below the nasal cavity. In front of Jacobson’s organ they 
are again connected by a short transverse vein, which corresponds topo- 
graphically to the sinus palatinus transversus posterior of the lizard. 
Behind this second anastomosis the two vene maxillares diverge, each 
vein running on the dorsal aspect of the interval which separates 
the maxillary and palatine bones. Under the anterior part of 
the orbit the vena maxillaris communicates anastomotically with the 
sinus orbitalis (c. m., Text Fig. 4) and with the vena palpebralis in- 
ferior (Text Fig. 4). As the lid vein is connected posteriorly with the 
sinus orbitalis, it forms a second channel of communication between the 
sinus and maxillary vein. Near the posterior end of the maxillary bone 
the vena maxillaris is joined by the vena palato-maxillaris, a vein which 
aids in forming a connection between the two venz maxillares across the 
roof of the mouth. Behind the mouth of the vena palato-maxillaris the 
vena maxillaris receives an anastomotic vein from the posterior prolon- 
gation of the sinus orbitalis, after which it passes under the transverse 
bone and enters the roof of the mouth. Here the vein continues caudad 
between the mucous membrane and the m. pterygoideus externus. Near 
the posterior part of the lachrymal gland the vein receives one or more 
additional anastomoses from the sinus orbitalis. Posteriorly the vena 
maxillaris meets the vena mandibularis a short distance in front of the 
junction of that vein with the vena jugularis interna. 
Anteriorly the two vene maxillares of the snake are much enlarged, the 
right and left veins being about equal. The left vein, however, dimin- 
ishes in size posteriorly, and as they approach the vena mandibularis the 
right vein (v. ma. d., Text Fig. 4) has two or three times the diameter 
of the left (v. ma. s.). 
Aside from the sinus orbitalis, which has already been described, the 
most important tributaries of the vena maxillaris are: (1) Vena ros- 
tralis, (2) sinus subnasalis, (3) vena subseptalis, (4) vena palatina 
obliqua. 
(1) Vena Rostralis (v. r., Text Fig. 4) —The subcutaneous tissue of 
the rostral region is occupied by a system of small veins which discharge 
into the vena rostralis. This vein crosses the middle line in front of the 
intermaxillary bone, then bends caudad on each side and runs on the 
lateral aspect of the jaw, until it reaches a point ventral to the external 
