i6o THE SALAMANDER 



In 1 9 1 7 Froriep, as the result of studying the larval stages of Sala- 

 mandra atra^ returned to Hoffmann's view. He found a sub-occipital 

 nerve which he regarded as the first spinal nerve, and came to the 

 conclusion that the atlas vertebra is a double one and therefore that 

 the first spinal nerve of the adult is morphologically the second. 



More recently, Mookerjee (1930) has shown that in Triton the 

 atlas, although it has a double origin, is not strictly a double verte- 

 bra (cf. 'atlas' in skeletal section). He finds the sub-occipital nerve, 

 however, and calls it N. spinalis i, and calls the hypoglossal nerve, 

 N. spinalis 2. 



To summarize: it seems certain, therefore, that the rudiment of 

 the nerve which appears between the occipital condyles and the verte- 

 bral column should be regarded as N. spinalis i, and that the next 

 posterior, which is the first spinal nerve of the adult, is morpho- 

 logically N. spinalis 2. Nevertheless since the N. suboccipitalis is 

 so very transient and probably never attains functional importance, 

 it seems unnecessary to insist on using the strict morphological 

 nomenclature, thereby confusing the description of all the remaining 

 spinal nerves. In the following account the nerves are accordingly 

 numbered as they appear in the adult, leaving the N. suboccipitalis 

 out of the series. 



The first spinal nerve arises from the spinal cord by two ventral 

 roots only. A dorsal root and a ganglion occur in the larva, but they 

 atrophy during metamorphosis. Driiner reports that in three out of 

 fifteen adults he finds a trace of the ganglion remaining, but such 

 a circumstance has not come under the notice of the present writer. 

 Correlated with the absence of the ganglion there is no dorsal cuta- 

 neous branch, but the dorsal muscular branches are present and 

 innervate the MM. intertransversarius capitis superior and inferior, 

 and the M. rectus capitis posterior. 



The R, ventralis passes directly ventral between the subvertebral 

 and dorsal musculature, and immediately on reaching the ventral 

 surface of the muscles it gives ofF (i) a very fine ramus communicans 

 ad sympatheticus (r.com.ad.sym.). It then turns somewhat postero- 

 laterally and gives off two more branches. 



(ii) A small twig to the M. intertransversarius capitis inferior 



(i.c.i.). 



(iii) One or two twigs to the M. opercularis (o.) as it passes ventral 

 to the edge of this muscle. 



At this point the nerve passes very close to the tenth cranial nerve 

 just at the point where the latter divides into gastric and pulmonary 

 branches. A very fine anastomosis is usually discernible at the 



