988 MRS. O. A. MERRITT HAWKES OX THE [DeC. 11, 



the end of the stalk and the beginning of the olfactory capsule. 

 On I'eaching this point, the nerve becomes somewhat enlarged by 

 flattening, then bi-eaks up into a number of fine branches which 

 passed towards the olfactory epithelium but coiild not be traced 

 to their endings. 



J. Summary. 



1. This paper is the first description of the cranial nerves of 

 Ghlamydose lachus . 



2. The cranial nerves of Chlamydoselachus ai'e not in as 

 primitive a condition as would be expected from the low position 

 of the species in the taxonomic series, especially as regards the 

 vagus and the lateralis nerves. 



3. The vagus arises by a sei^ies of roots, which, however, cannot 

 be assigned to the separate rami. 



4. The ganglia of the vagus cannot be separated completely by 

 gross methods. 



5. The number of roots by which the lateralis components 

 arise confirms the suggestion that, in origin, the acoustico-lateralis 

 components belonged to a series of segments. r-i^"-' 



6. The connections between the acoustico-lateralis elements of 

 v., VII., snd YIII. show a tendency towards unification of the 

 system. 



7. The glossopharyngeus includes a lateralis component. 



8. The r. lateralis vagi unites closely with the true Vagus in 

 the ganglionic region. 



9. Locy's nerve is large and well-defined. 



10. The roof of the prosencephalon and of the olfactoiy stalk 

 was non-nervous in the immature specimen examined. 



11. There is a direct nei'vous connection between the r. pro- 

 fundus and the oculo-motor nerve. 



12. The profundus nerve here appears as a ramus of the tri- 

 geminal nerve. 



13. The trigemino -facial complex is less j)rimitive than tliat of 

 Chimcera, but more so than that of most Elasmobranchs. 



14. The facialis is in an unusually primitive condition, in that 

 it has a remnant of the post-trematic ramus quite separate from 

 the t. hyomandibularis. 



15. With our present knowledge, we are justified in stating- 

 that a, chorda tympani is present. 



16. There is a sixth r. branchialis vagi which passes towards 

 the remnants of the seventh arch. 



17. There is a tendency towards a reduction of the rami 

 pre-branchialis vagi, thus leading to a condition found in some 

 Teleosts. 



18. There is a hypoglossal nerve. 



19. The spiracle is small and opens into the hyo-branchial cleft. 



20. The ampullae of Lorenzini are arranged diftusely. There is 

 no hyomandibular group, but there is a posterior buccal group. 

 The ampnllse have a simple structure. 



