No. 2.] ENTERON OF AMERICAN GANOIDS. 433 



7. The boundary line between oesophagus and stomach can 

 be determined only by microscopical examination. 



8. In the sturgeon, Scaphirhynchops, Polyodon, and Amia 

 deep follicles are found cephalad of the pneumatic duct open- 

 ing. In Lepidosteus the pneumatic duct opens very far in 

 front of the place where the follicles first make their appear- 

 ance. In sturgeon and Scaphirhynchops true gastric cells (as 

 inferred from their form and appearance) are present cephalad 

 of the pneumatic duct; that is, to all appearances, in these 

 two last named forms the pneumatic duct opens into the 

 stomach. 



9. The typical form of transition from the stratified epithe- 

 lium of the oesophagus to the columnar epithelium of the 

 stomach is illustrated in Fig. 7. The columnar and stratified 

 epitheliums are wedge-shaped at the place of transition, the 

 columnar overlying the stratified epithelium. 



10. A basement membrane could not be demonstrated in 

 any of the individuals examined. 



1 1 . The ontogenetic development of the glands shows that 

 primitively they were lined throughout their whole length by 

 cells like those of the surface epithelium. The true glandular 

 cells are a later specialization; hence those glands with a com- 

 paratively long mouth and short glandular portion are regarded 

 as more primitive than those with a short mouth and long 

 glandular portion. 



12. From the above statement we conclude that the gastric 

 glands of Lepidosteus are somewhat more highly specialized 

 than those of Amia, and that both these are more highly 

 developed than in any other members of the order. 



13. Pyloric caeca are present in all except Amia; a spiral 

 valve is present in all, being most rudimentary in Lepidosteus. 



14. Ciliated cells were found in the oesophagus and stom- 

 ach of all the members of the group examined. 



15. Ciliated cells were not found in the pyloric region of 

 the stomach, either on the free surface or in any portion of the 

 glands. 



16. The significance of cilia in the enteron is doubtful. 

 Trinkler thinks they have not much meaning; he regards them 



