THE EMBRYOLOGY OF CRYPTOBRANCHUS ALLEGHE- 



NIENSIS, INCLUDING COMPARISONS WITH 



SOME OTHER VERTEBRATES 



II. GENERAL EMBRYONIC AND LARVAL DEVELOPMENT, WITH 

 SPECIAL REFERENCE TO EXTERNAL FEATURES^ 



BERTRAM G. SMITH 



From the Zoological Laboratory of Columbia University 



TWO HUNDRED AND TWENTY -THREE FIGURES (EIGHT PLATEs) 



CONTENTS 



VI. Introduction 455 



VII. Cleavage 458 



A. Description by stages 458 



B. Summary 485 



VIII. Gastrulation and early formation of the embryo 486 



A. Description by stages 486 



B. Summary 518 



IX. Development after the closure of the neural folds ^ 519 



A. Description by stages to the time of hatching 519 



B. Larval development, and the metamorphosis 528 



C. Post-larval stages 531 



D. Summary 532 



X. Time record 533 



XT. Abnormalities 533 



XII. Phylogeny 540 



Bibliography 558 



VI. INTRODUCTION 



The present contribution is one of a series of papers on the 

 embryology of Cryptobranchus, of which Part I, deaUng with 

 the breeding habits, ovogenesis, maturation and fertilization, 

 has already been pubhshed (Smith '12). In the preparation of 



1 Part I was published in the Journal of Morphology, vol. 23, no. 1, March, 1912, 



455 



