No. 2.] ENTERON OF AMERICAN GANOIDS. 423 



pneumatic opening. The epithelium of this region is strati- 

 fied; the surface layer is composed chiefly of large beaker-cells 

 almost bladder-like in form; the nuclei are quite small and 

 crowded down close to the attached ends of the cells. Near 

 the place where the papillae disappear the stratified is suc- 

 ceeded by a ciliated columnar epithelium. The arrangement 

 of the cells at the point of transition of the two epitheliums is 

 as in the preceding form, i.e., the ciliated cylindrical cells 

 overlie the deeper layers of the stratified oesophageal epi- 

 thelium as in Fig. 7. 



The segment of enteron between this point and the opening 

 of the pneumatic duct is, from the presence of glandular cells, 

 regarded as the cephalic part of the gastrium. The stomach 

 glands of the individual examined were not so long as those in 

 the sturgeon; the comparative length of the mouth and glandu- 

 lar portion was, however, about the same proportion, i to 3 

 nearly (Fig. 13). 



The mouths of the glands, except the pyloric, are lined by 

 ciliated cells resembling those of the surface epithelium (Fig. 

 16). Among the ciliated epithelial cells are many greatly dis- 

 tended beaker-cells whose contents are coarsely granular and 

 very sharply differentiated from the neighboring cells (Fig. 16). 

 The granulation extends into the cell to the level of the nu- 

 cleus. In some instances the granular mass could not be seen 

 projecting beyond the level of the free ends of the cells, but 

 in others this was noticed. Probably in the former the theca 

 had not yet ruptured and the contents exuded as in the latter. 

 The nuclei of the great majority of these cells were situated 

 at a higher level than the others, as if the swelling caused by 

 the granular accumulation within had started the cells some- 

 what from their normal position. Although these two kinds 

 of cells are so different in appearance, it is not easy to deter- 

 mine in precisely what this difference consists. 



Trinkler thinks that the only difference between beaker-cells 

 and the ordinary cylindrical cells is, that in the former the 

 metamorphosis of the protoplasm is more complete; he con- 

 siders the beaker-cells as simply a later condition of the cylin- 

 drical cells. 



