298 ZOOLOGY, 



4. (a) What are the protovertebrso ? (b] How does the 

 notochord originate in the frog ? (c) How are the vertebrae 

 laid down in the tadpole? (d) Describe the vertebral 

 (jolumn of the adult frog, (e) In what important respects 

 do the centra of the vertebrae of the frog, the dogfish, and 

 the rabbit, differ from one another ? 



5. What temporary organs are developed in the embryo 

 frog which are absent from the embryo bird and mammal, 

 and what in the two latter which are absent from the 

 former ? 



6. Describe fully the coelom of Amphioxus, and compare 

 it with that of the frog in regard to (a) development, (b) its 

 relatiqjL to other organs in the adult. 



7. How do protozoa differ from higher animals (metazoa) 

 as regards (a) structure, (5) reproduction? Compare the 

 process of fission in an amoeba with the segmentation of the 

 ovum in Amphioxus, pointing out the resemblances and 

 differences between the two cases. 



8. Compare the auditory organs in Scyllium, Rana, and 

 Lepus, especially with regard to the homologies of the 

 structures connected with the tympanic cavity, namely 

 the auditory ossicles, the columella, and the Eustachian 

 tube. Describe the course of the 7th cranial nerve in each 

 case. 



9. Trace the history of the post-oral gill- slits and their 

 accompanying cartilaginous bars and vascular arches in the 

 frog, fowl, and rabbit. 



10. Give a short account, with illustrative figures, of the 

 mode of formation of the primary germinal layers in Am- 

 phioxus and in the frog. What explanation can you give 

 of the differences between the two cases ? 



11. Give a short account, with diagrammatic figures, of 

 the principal changes which occur in the circulatory and 

 respiratory organs during the metamorphosis of the tadpole 

 into the frog. 



12. Describe the mode of development and adult struc- 

 ture of the vertebrate eye. 



Explain the position of the retinal layers, illustrating 

 your answer by a careful comparison with the eye of the 

 cravfish. 



