428 HOPKINS. [Vol. XI. 



three preceding forms do not exist in Lepidosteus, owing, possi- 

 bly to the great development of the dental armament, which 

 practically precludes the escape of prey, when once fairly with- 

 in the mouth, without any intervention of subsidiary struc- 

 tures. 



In Lepidosteus^ the non-glandular cephalic portion of the 

 enteron extends from the pneumatic duct caudad a distance of 

 8 to 10 cm. before the gland structures of the stomach appear. 

 This part, which will be called oesophagus, is covered by a 

 ciliated columnar epithelium interspersed with numerous beaker- 

 cells (Fig. 17). In front of the pneumatic opening the epithe- 

 lium is stratified, being composed principally of large mucous 

 cells, but among these are a considerable number of cylindrical 

 and fusiform cells. Owing to the rounded form of the beaker 

 or mucous cells, the nuclei, situated close to the attached end 

 of the cells, presents a disk-like or saucer-shaped appearance. 

 Of the epithelium of the stomach of fishes Edinger says (Ueber 

 die Schleimhaut des Fischdarmes nebst Bemerkungen zur 

 Phylogenesis der Driisen des Darmrohres, p. 666), " Cilia, 

 where such cover the mucous membrane of the oesophagus, 

 disappear in the stomach. . . . The epithelium of the stom- 

 ach is a cylindrical epithelium which never bears cilia." Possi- 

 bly these statements are true for all the specimens he exam- 

 ined, but the probabilities are that he overlooked the cilia in 

 the stomach of Lepidosteus. The grounds for this belief are, 

 first, he himself found ciliated epithelial cells in the oesophagus 

 of Lepidosteus ; and second, as already stated, the oesophagus 

 in the present specimen is ciliated, but ciliated cells were found 

 in the stomach as well. Possibly the reason for Edinger not 

 finding them was due to defective preservation of the cilia in 

 this region. Cilia were not found over the whole extent of the 

 cardiac region, but were confined to its cephalic part. The 

 ciliated cells did not form a continuous layer but were more or 

 less scattered among the nonciliated epithelial cells of this 

 region. 



The epithelial cells are long and slender; the thread-like 



1 Size of specimen not known, but the hardened specimen of oesophagus and 

 stomach measured somewhat over twenty centimeters. 



