222 THE SALAMANDER 



important factors of the V. jugularis lateralis. It collects the blood 

 from muscles of the neck region on the dorsal side of the vertebral 

 column. It passes anteriorly dorsal to the M. opercularis and the Xth 

 nerve, and mesial to the I Xth nerve to join the main vessel posterior 

 to the IX+X ganglion. 



Very frequently, but perhaps not quite constantly, the vertebral 

 veins may be traced right through the dorsal muscles to the ventral 

 side, appearing just anterior to the transverse process of the second 

 vertebra. They then pass backwards alongside the vertebral column 

 to join the post-cardinals at the point where they turn lateralwards 

 to loop around the oesophagus. An anastomosis from the palatal 

 region is also frequently received at the point where they emerge on 

 the ventral surface of the muscles. The connexion with the post- 

 cardinal veins is primitive, and in the Frog, where the post-cardinals 

 are absent, the vertebral veins discharge entirely into the internal 

 jugular veins. 



(d) Another considerable tributary of the V. jugularis lateralis is 

 an anastomosis with the V. pharyngo-palatina. It arises somewhat 

 variously, either from the V. pharyngo-palatina itself, or from its 

 mandibular factor, or even from the V. petrosa lateralis. It enters 

 the V. jugularis lateralis ventrally just posterior to the columella. 



(e) The only other tributary of note is the dorsal branch of the V. 

 ■petrosa lateralis. This vessel leaves the V. petrosa lateralis within the 

 antrum, and emerges between the columella and the processus oticus, 

 looping round the ^orWside of the columella to enter the V. jugularis 

 lateralis dorsally. 



Factors of the V. pharyngo-palatina . 



(a) V. petrosa lateralis (Driiner) (v.pet.l.). 



V. capitis lateralis ....... Goodrich. 



V. lateralis ........ Osawa. 



This is the vessel which passes through the space between the palato- 

 quadrate and the otic capsule — the antrum petrosum laterale. It 

 drains the cranial cavity and the orbit by several factors as follows : 

 The peri-orbital network (p.o.n.) (see also PI. XIII, fig. 58) is a 

 wide venous girdle completely surrounding the bulbus oculi. It may 

 be said to originate at the anterior border of the orbit where it re- 

 ceives the V. nasalis (v.na.) from within the nasal capsule, and a 

 medium-sized cutaneous vein from the skin overlying it — F. fron- 

 talis (v.fr.). The network lies mainly, but not entirely, deep to the 

 eye-muscles, and drains them as well as the tissues of the orbit 

 generally. It is hardly possible to differentiate any particular vessel, 



