424 HOPKINS. [Vol. XL 



The bodies of the gastric glands are made up of irregularly 

 cubical-shaped cells which overlap each other as in the stur- 

 geon. The cells are granular in appearance; the nuclei are 

 large, and contain a distinct nucleolus. That portion of the 

 cell next to the lumen of the gland stains much less deeply 

 than the basal half of the cell. Usually more than one gland 

 opens in a single mouth ; the usual number was two, but fre- 

 quently three or more were noted. The glands lie in close 

 proximity to each other, there being but little intervening con- 

 nective tissue. 



In surface sections, i.e., sections at right angles to the long 

 axis of the gland, it was noticed that frequently several glands 

 were united, as it were, into a bundle; the connective tissue 

 surrounding these forming a thicker layer than around the 

 individual glands. As seen in cross-section, the number of 

 epithelial cells of a gland varies from eight to twelve in most 

 instances (Fig. 14). 



POLYODON. 



The appearance of the enteron in this genus differs some- 

 what from either of the preceding. Its general outline is shown 

 in Fig. 3. The papillae at the cephalic end of the oesophagus 

 are small and numerous; they extend to within about one or one 

 and one-half centimeters of the pneumatic duct. The walls of 

 the stomach are considerably thicker than in either of the pre- 

 ceding specimens. At the pyloric valve the muscular walls 

 are thickened as in Scaphirhynchops. The pyloric caeca are 

 relatively much larger and more deeply subdivided (Fig. 3, c). 

 The caecal cavity communicates freely with that of the intes- 

 tine; it subdivides into four main branches, corresponding to 

 the four main lobes into which the gland is divided. The in- 

 testine is short, morphologically speaking, but the spiral valve, 

 with its six complete turns, really forms a long intestine, in a 

 physiological sense. The last turn of the valve is about two 

 centimeters from the vent. The peritoneal coat is almost en- 

 tirely unpigmented, there being only a few small pigment 

 patches. 



