CRANIAL NERVES OF CAECILIANS 549 



In Geotrypetes, Dermophis and Caecilia an important branch 

 of the occipital nerve combines with a branch of the first spinal 

 nerve to form the hypoglossal nerve. 



According to Fischer, both the first and second spinal nerves 

 in Siphonops enter the sympathetic ganglion, and the hypoglos- 

 sus emerges from the latter. Wiedersheim states that in Ich- 

 thyophis the hypoglossus is formed by the union of a branch of 

 the first spinal nerve, which has passed through the sympathetic 

 ganglion, with a ventral branch of the second spinal nerve, the 

 latter not passing through the ganglion. The writers find that 

 in the larva and adult of Ichthyophis neither the first nor the 

 second spinal nerve passes through the sympathetic ganglion. 

 Waldschmidt designates the second spinal nerve in Siphonops 

 as the first, the true first spinal nerve becoming his hypoglossus. 

 He finds no fusion with the second spinal nerve. Marcus sees 

 in Hypogeophis a union of the first and second spinal nerves to 

 form the hypoglossus. In the larva of Ichthyophis ventral 

 branches of the first, second, and third spinal nerves unite in a 

 hypobranchial nerve, from which, after turning ventrally and 

 anteriorly, there are given off sensory and possibly motor branches, 

 leaving the hypoglossus anteriorly. 



THE SECOND SPINAL NERVE 



The second spinal nerve has the full complement of a typical 

 spinal nerve, with dorsal and ventral roots. Three main rami 

 pass out of the ganglion: 1) a dorsal of mixed constitution, pass- 

 ing dorsally around close to the lateral border of the vertebra, 

 thence up through the dorsal muscles near the middle line, to be 

 distributed to the dorsal skin and the dorsal trunk musculature 

 (fig. 44, sp.2d.); 2) a lateral cutaneous branch passes later- 

 ally out through the ventral part of the dorsal musculature in an 

 almost horizontal position until it reaches the lateral portion of 

 the musculature, where it divides into anterior and posterior 

 branches distributed to the skin {sp.2l.); 3) a ventral branch of 

 mixed composition directed laterally and posteriorly out through 

 the notch formed by the tubercular and capitular processes of 



