CRANIAL NERVES OF CAECILIANS 505 



on the walls of the tentacular canal anterior to the eyeball (figs. 

 11, 12, so. and to.). The po.sition and relations of these muscles- 

 indicate that they are the dorsal and ventral oblique muscles. 

 The muscles of the second set originate close together posterior 

 to the eyeball, from the fibrous envelope of the retractor ten- 

 taculi muscle and of the compressor muscle of the orbital gland 

 (fig. 14, rs. and rinf.). They seem to correspond to the dorsal 

 and ventral rectus muscles. Besides these four muscles a small 

 muscle slip, originating near the point of origin of the preceding, 

 runs to the posterior border of the eyeball, representing appar- 

 ently a rectus lateralis (fig. 14, rext.). Along with the optic 

 nerve, from the retractor tentaculi muscle to the eyeball, there 

 runs a bundle of coarse fibers which seems like a rudimentary 

 muscle, a retractor bulbi. Of a rectus medialis there seems to be 

 no trace. 



In Dermophis the eye-muscle nerves occur in their typical 

 arrangement. As in all amphibians, when the eye is rudiment- 

 ary, the fourth nerve is the least developed. The sixth, supplying 

 the retractor tentaculi muscle, is the only one of considerable 

 size. The oculomotorius was traced to within two or three sec- 

 tions of the origin of the muscle considered as the rectus dorsalis. 

 The relation of the nerve to the rectus ventralis and the obliquus 

 ventralis could not be determined, but is doubtless as has been 

 described in other amphibians. Its innervation of a levator 

 bulbi (compressor of the orbital gland), as stated by Marcus in 

 Hypogeophis, was not found. An anastomosis of the oculomo- 

 torius with the ramus maxillaris V, such as was reported by 

 Waldschmidt in Siphonops, certainly does not occur in Dermo- 

 phis. The fourth nerve in Dermophis is extremely attenuated. 

 It was traced some distance from its point of emergence from 

 the brain along the medial border of the parietal bone, but was 

 finally indistinguishable from the fibrous envelopes of the brain. 

 The abducens nerve innervates the retractor tentaculi muscle 

 and is correspondingly of considerable size. Owing to the poor 

 differentiation of small nerves in the specimen of Dermophis, it 

 was impossible to determine any relation of the abducens to the 

 vestigial rectus lateralis muscle or to a retractor bulbi. In 



THE JOtRNAL OF MOKPHOLOGT, VOL. 31, NO. 3 



