THE SKELETON OF THE DOGFISH. THE SKULL. 75 



foramen is another small aperture, the foramen for the 

 third nerve. Behind and slightly below this is the large 

 foramen for the sixth and main branches of the fifth 

 and seventh nerves (fig. 6, V.). In front of and slightly 



IX 



FIG. 6. LATERAL VIEW OF THE SKULL OF A DOGFISH (Scyllium 

 canicula) x f . 



1. nasal capsule. 



2. rostrum. 



3. interorbital canal. 



4. foramen for hyoidean artery. 



5. foramen for the exit of the 



ophthalmic branches of 

 Vth and Vllth nerves. 



6. foramen through which the 



external carotid leaves the 

 orbit. 



7. orbitonasal foramen. 



8. auditory capsule. 



9. foramen through which the 



external carotid enters the 

 orbit. 



10. ethmo -palatine ligament. 



11. palato-pterygo-quadrate bar. 



12. Meckel's cartilage. 



13. hyomandibular. 



14. cerato-hyal. 



15. pharyngo-branchial. 



16. epi-branchial. 



17. cerato-branchial. 



18. gill filaments, nearly all have 



been cut off short for the 

 sake of clearness. 



19. extra-branchial. 



20. pre-spiracular ligament. 



II. III. IV. V. Va. Vila, foramina 

 for passage of cranial nerves. 



below this foramen are seen two other small apertures; the 

 more anterior and ventral of these (fig. 6, 4) is for the 

 passage of a vessel connecting the efferent artery of the hyoid 

 gill with the internal carotid artery inside the skull, the more 



