224 THE SALAMANDER 



extraordinarily variable. The whole region is highly vascular, and 

 anastomoses are frequent, so that the several main vessels may vary 

 considerably in size and extent from specimen to specimen or even 

 on the two sides of the same individual. 



The most mesial of them is the V. palatina (v.pal.). It arises 

 by many fine tributaries from the region of the internal nares and 

 from the mucous membrane covering the pre-vomer, and, follow- 

 ing the curve of the posterior tooth-bearing process of this bone, 

 drains the rich vascular network surrounding the bases of the 

 teeth. Just in front of the dorsal portion of the systemic arch the 

 palatine vein drains a venous plexus forming a coarse network on the 

 roof of the pharynx in the middle region between the occiput and 

 the posterior ends of the pre-vomerine teeth (pi. ph.). It then turns 

 sharply laterally, and, following the curve of the systemic arch, joins 

 the pharyngo-palatine vein at the side of the pharynx a short distance 

 before this vein itself unites with the V. jugularis lateralis to form 

 the internal jugular. 



The vein just described lies mesial to the nerve and to the palato- 

 nasal artery, but there is also a vein lateral to these structures which 

 may accordingly be called the lateral palatine vein (v.pal. 1.). It re- 

 ceives its blood from the mesial part of the floor of the orbit — from 

 the M. levator bulbi, and the mucous membrane of the roof of the 

 mouth — and may be distinguished from the V. orbitalis inferior in 

 that it lies ventral to the M. levator bulbi. It nearly always joins the 

 V. anastomotica of the V. petrosa lateralis and not infrequently the 

 V. palatina also, but either of these connexions may be absent. 



The V. maxillo-palatina (v. max. pal.) drains the anterior part of the 

 upper jaw, and, at about the middle of the orbit, turns mesialwards 

 and crosses obliquely towards the postero-mesial corner of the orbit. 

 Here it may join the V. anastomotica and so empty itself into the V. 

 petrosa lateralis, or it may pass somewhat more lateralwards and dis- 

 charge into the V. pharyngo-palatina direct, while both connexions 

 may be present. When it enters the V. pharyngo-palatina direct it 

 does so close to the point where the V. petrosa lateralis and the V. 

 mandibularis profunda are received. 



The V. mandibularis prof unda (v.m.pf.) arises from an anastomosis 

 with the internal mandibular vein (a factor of the external jugular, 

 q.v.) just posterior to the N. intermandibularis. It passes backwards, 

 dorsal to the MM. interhyoideus and interhyoideus posterior, receiv- 

 ing blood from the former muscle, as well as numerous tributaries 

 from the floor of the mouth between the lower jaw and the base of 

 the tongue. Sometimes two vessels may enter the V. pharyngo-pala- 



