ALIMENTARY CANAL IN LEPIDOSIREN AND PROTOPTERUS. 483 
On Certain Features in the Development of the 
Alimentary Canal in Lepidosiren and 
Protopterus. 
By 
J. Oraliaiii Kerr, 
Professor in the University of Glasgow. 
Witli 13 Text-figures. 
Contents. 
PAGE 
I. Introduction ...... 
II. Diiferentiation of the Main Regions of the Alimentai’y Canal 
III. Buccal Cavity ..... 
IV. Lung ...... 
V. Pancreas ...... 
VI. Sunimaiy ...... 
483 
484 
494 
501 
513 
517 
I. Introduction. 
The following pages contain a short description of certain 
features which have seemed of special interest in the develop- 
ment of the alimentary canal of Lepidosiren and Proto- 
pterus. 'The technical methods used have been the same as 
those used in earlier stages of my work. In particular, I have 
made constant use of the method of reconstruction by means 
of ground glass plates, and I have endeavoured to use both 
the celloidin and the paraffin methods of embedding. As I 
have already had occasion to point out more than once, it is, 
in my opinion, essential in embryological investigations to 
use these methods side by side. Both are liable to mislead, 
both have their faults, but the faults are different in the two 
VOD. 54, PART 4. NEW SERIES. 35 
