i8o THE SALAMANDER 



the connexion described by Hoffmann between the vagus ganglion 

 and the first spinal nerve is doubtless identical with that interpreted 

 here as the spino-occipital nerves (see p. 156). 



2. Description. 



Following Andersson's arrangement, it is most convenient to 

 describe the system in three sections, viz. (i) the cephalic -portion^ 

 anterior to the ramus communicans to N. spin, i, (ii) the cervical and 

 abdominal portions continuing from the posterior extremity of the 

 cephalic portion to the commencement of (iii), the caudal portion^ 

 lying within the haemal canal. It is further convenient to describe 

 sections (ii) and (iii) before dealing with the more difficult and 

 obscure cephalic section. 



(ii) The cervical and abdominal portions (PL XVII, fig. 64). In 

 general arrangement the sympathetic system consists of ganglia 

 arranged in a paired longitudinal series on either side of the dorsal 

 aorta, connected serially with each other by a chain of nerve 

 fibres, and transversely with the ventral rami of the spinal nerves by 

 the rami communicantes. There are also several cross-connexions 

 between the two longitudinal series which will be mentioned sub- 

 sequently. 



The most anterior ganglion of this section — i.e. the one receiving 

 the r. comm. n. sp. i — is very small, as also is the next, but the third 

 ganglion, lying immediately anterior to the subclavian artery, is a 

 large one. It receives the r. comm. n. sp. 3. This section is called by 

 Andersson the cervical portion. Anastomoses between the two sides 

 occur in this region, both dorsally and ventrally to the aorta, and they 

 usually pass obliquely from the second to the third ganglia. The 

 nerve chain of each side in this section is usually double, and often 

 treble, while sometimes it becomes so subdivided that it almost dis- 

 appears. 



The ganglion associated with the r. comm. n. sp. 3 is the anterior 

 subclavian ganglion (Andersson) and from it emerge three, or some- 

 times four, nerves. Two of these pass to the gang, subclav. postr. 

 (Andersson), one lying dorsal, and the other ventral to the sub- 

 clavian artery. The dorsal nerve is very much stouter than the ven- 

 tral. The third constant branch is a lateral one passing along the 

 anterior side of the subclavian artery to the fore-limb. On the 

 animal's right side this nerve bears a small ganglion situated about 

 a millimetre from the dorsal aorta. This ganglion has not been 

 observed on the left-hand side. It is usually connected with the pos- 

 terior subclavian ganglion by a fine nerve which crosses the sub- 



