492 H. W. NORMS AND SALLY P. HUGHES 



Like Wiedersheim and Waldschmidt, he fails to find a trochlearis 

 or an abducens. He recognizes four roots in the acusticus, three 

 roots in the glossopharyngeus, and seven roots in the vagus. He 

 finds two distinct divisions in the IX to Xth ganghon of the 

 embryo: an anterior small-celled portion and a posterior part 

 with large cells. From the vagus ganglion he derives a cervical 

 sympathetic ganglion, which remains connected with the vagus 

 by a large nerve trunk. The double nature and origin of the 

 fifth nerve is shown by figures of the embryo of Ichthyophis. 



According to Brauer ('04), the double condition of the fifth 

 nerve in Hypogeophis is related to the distinct origins of the two 

 parts in the embryo, the ophthalmic ganglion coming from a 

 dorsolateral placode, and the maxillomandibular ganglion from 

 the neural crest. 



Marcus ('10) has given us a thoroughgoing account of the 

 sti-ucture of the caecilan head and the homologies of the organs 

 therein represented. An examination of his figures shows that 

 the cranial nerves of a caecilian are fundamentally like those of 

 other Amphibia. He finds all three eye-muscle nerves repre- 

 sented in the embryo, with the characteristic distribution. The 

 sixth nerve, besides supplying the rectus lateralis muscle, in- 

 nervates the retractor tentaculi, the latter probably a retractor 

 bulbi in origin. The fourth nerve is very small, but of the eye- 

 muscle nerves the third nerve is the largest. Besides its char- 

 acteristic distribution, he believes that it supplies the levator 

 bulbi muscle. He agrees with Brauer as to the origin of the 

 fifth nerve. It is evident that the facialis contains in the embryo 

 a complete lateral line component: rami ophthalmicus super- 

 ficialis, buccalis, and probably mandibularis externus. A ramus 

 recurrens VII passes posteriorly around the ear capsule to unite, 

 not with the ninth or tenth nerves, but with the great cervical 

 sympathetic ganglion. In the IX to X complex he finds eight to 

 ten roots. The ganglion in the embryo is plainly double, an 

 anterior ninth and a posterior tenth ganglion. In one stage he 

 figures the tenth ganglion as double. The ninth nerve (first 

 branchial) shows a division into pre- and post-trematic branches. 

 The second, third, and fourth branchial nerve divisions of the 



