x iv CONTENTS. 



CHAPTER IX. 



The Development of the Skull, pp. 225 — 238. 



1, 2. The primordial cranium. 3, 4. The investing mass of Ratlike. 

 5. The trabecular cranii. 6. The cartilages of the first visceral arch. 7. 

 The maxillary process. 8. The mandibular arch. 9. The hyoid arch. 10. 

 The cartilages of the third visceral arch. ] r. Changes in the cranium during 

 the fifth and sixth days. 12. During and after the seventh day. 13. The 

 condition of the cranium at about the middle of the second week. 14. Ecto- 

 steal and endosteal ossifications of the cartilaginous cranium. 15. Formation 

 of the membrane bones. 16. Progress of ossification during the second and 

 third weeks. 17. Fenestration of the ethmo-presphenoid cartilage. 18. Ossifi- 

 cations in the prootics and alisphenoid. 19. Changes in the basitemporals. 

 Formation of the vomer. 20. The changes which take place immediately 

 after exclusion from the egg. 21. Further changes in the splint bone3. 

 Coalescence of the bones after birth. Table of bones classified according to 

 their mode of ossification. 



APPENDIX. 



Practical Instructions for studying the Development of the Chick, 



PP- 2 39~ 26 7- 



I. Incubators. II. Examination of a 36 to 48 hours embryo. III. 

 Examination of an embryo of about 48 — 50 hours. IV. Of an embryo at the 

 end of the third day. V. Of an embryo of the fourth day. VI. Of a 

 blastoderm of 20 hours. VII. Of an unincubated blastoderm. VIII. Of the 

 process of segmentation. IX. Of the later changes of the embryo. X. Study 

 of the development of the blood-vessels. 



ERRATUM. 



124, in the description of Fig. 39 B, for 'Superior vertebral' substitute 



'Jugular.' 



