488 



PROP*. G. S. THA^AR OH 1'hB 



jugular vein. The second plexus occurs a little higlier up, near- 

 the hyoid, from which it receives branches (h.). The third and 

 fourth plexuses are near each other, on the floor of the buccal 

 cavity. The formation of plexuses between the external jugular 

 veins is essentially an avian character, and I am not aware that 

 it has hitherto been described in any Lacertilian. 



The Anterior Vena Cava and its branches. 

 a.v.c, anterior vena cava; a»i., antebrachial; br., brachial; e.J., external 

 jugular; 7i., hyoidean ; t.^'., internal jugular; /., lateral vein ; j?., pectoral ; 

 pr.br., prebrachial ; s., subclavian ; ss., subscapular. 



(2) The Internal, Jugular Vein (i. J.) receives a short vessel, the 

 lateral vein (?.), from the hinder region of the neck. 



(3) The Prebrachial (pr.br.) joins the vena cava at the junction 

 of the neck with the body. It is a vessel of fair size, running 

 along the preaxial border of the arm. 



(4) The Subclavian Vein (s.) is a very large vessel running 

 along the postaxial side of the arm ; it receives many branches 

 from the arm, shoulder, and chest, the chief of which are 



(a) Subscapular (ss.), from the muscles of the back, 



(b) Pectoral (j>-), from the pectoral muscles, 



(c) Brachial (br.), from the arm and hand, 



(d) Antebrachial (an,), from the forearm. 



(5) The Azygos Fein (text-fig. 3,az.), which enters the right 

 anterior vena cava, is a fairly large vessel formed by the union of 

 two branches, a vei-tebral (v.) from the vertebral column, and a 

 parietal (pa.) from the body- wall. Beddard states that in 

 V. griseus the parietal branch of the azygos is connected with 



