572 DR. C. F. SONNTAG ON THE COMPARATIVE ANATOMY 



reaches the right renal vein. After that it bends to the right 

 and enters the liver. At the point where it disappears from 

 view it is in contact with the right suprarenal capsule, and is 

 accompanied by twigs from the right half of the solar plexus. 



The left ovarian vein (text-fig. 61 0, ov.) joins the thick venous 

 plexus running along the ureter ; therein it is united to veins 

 ascending from the pelvis. The right ovarian vein communicates 

 with the right ureteric veins by a stout trunk, and then runs 

 forwards to join the postcaval vein. The ureteric veins (tiv. and 

 wy.)form a plexus on the ventral surfaces of the renal pelves and 

 open into the renal veins (rv.). 



The Nervous System, 



The hxiin has been described by Owen (11), Forbes (4), Elliot 

 Smith (12), and Ziehen (14), and I have nothing to add to their 

 accounts. 



The Vagus Nerves (text-figs. 62 and 63). 

 Phascolarctos cinereus. 



A short distance posterior to the base of the skull the vagus 

 nerve on each side receives the hypoglossal (XII.) nerve, and their 

 fibres intermingle in a very thorough manner. Soon they 

 separate again, and tlie vagus runs postero-mesially as far as the 

 anterior extremity of tlie thyroid cartilage, where it vinites with 

 the cervical sympathetic cord(C.S.)to form a vago-sympathetic 

 (Y-S.). A short distance anterior to the clavicle it separates again 

 into vagus (V.) and sympathetic (S.). 



This arrangement is present in most of the Carnivora. It 

 diff"ers from that of Dendrolagus, in which the vagi and sym]^- 

 thetics remain separate. 



There is no ti-ace of the ganglion of the trunk of the left 

 vagus (ganglion nodosum) in the neck. The right nerve has 

 one (G.N.). 



Branches in the neck. — Pharyngeal {a), anterior laryngeal (6), 

 commianicating to the first cervical nerve (c), and recurrent 

 branch of the right vagus {d). 



The relations of the vagi in the thorax differ. The left nerve 

 crosses superficial to the left subclavian arter}^ and aortic arch, 

 lying on the inner side of the left precaval vein and left phrenic 

 nerve, and on the outer side of the trachea, cesophagus, and left 

 common carotid arteiy. It passes dorsal to the root of the left 

 luno- and gains the dorsal aspect of the oesophagus. The right 

 nerve crosses the right subclavian artery under cover of the 

 right precaval vein, runs down the side of the right main 

 bronchus, and gains the dorsal aspect of the root of the right 

 lung; lastly it passes to the dorsal aspect of the oesophagus, 

 where it fuses with the left nerve to form the combined trunk of 

 the vagi (C.T.V.). 



