(b) The uro-genital apertures, instead of meeting dorsally and posteriorly to the anus, to shift round that opening and meet anteriorly and ventrically to it. Section 21. This completes our survey of this type. Except where we have specified differences, the general plan of its anatomy follows the lines of the other vertebrate types described. _Questions on the Dog-Fish_ 1. Describe the alimentary canal of the dog-fish, and compare it with that of the rabbit in detail. 2. Compare the coelom of the dog-fish and rabbit. 3. Draw diagrams to illustrate the course of the circulation in the dog-fish. 4. (a) Describe fully the heart of a dog-fish. (b) Compare it with that of a rabbit. 5. Give an account of the respiratory apparatus of the dog-fish. 6. Draw diagrams of a dog-fish vertebra, and compare the centrum with that of a rabbit. 7. Compare the vertebral column of the dog-fish and rabbit. 8. Draw diagrams of the limbs and limb-girdles of the dog-fish. Compare the pectoral with the pelvic fin. 9. Draw diagrams of (a) the male and (b) the female urogenital organs of the dog-fish. (c) Compare them carefully with those of the rabbit. 10. Compare the circulation in the kidney of dog-fish and rabbit. 11. Give an account of the cranio-facial apparatus of the dog-fish. State clearly what representation of this occurs in the frog and in the rabbit. 12. Give drawing (a) from above, (b) from the side, of the dog-fish brain. 13. State the origin and the distribution of the fifth, seventh, ninth, and tenth cranial nerves in the dog-fish. 14. Compare, one by one, the cranial nerves of the dog-fish with those of any higher vertebrate, as regards their origin and their distribution. 15. Describe the auditory organ of the dog-fish. What parts are added to this in the higher type? 16. Draw the cloaca (a) of a male, (b) a female dog-fish. 17. (Practical.) Demonstrate in a dog-fish the pathetic nerve, the opening between pericardium and coelom. the abdominal pores, and the ureter. -Amphioxus_ 1. _Anatomy_