376 Grant Sherma7i Hopkins 



side of the air-bladder, opens into the large lymph sinus at 

 the right side of the oesophagus. The termination of the en- 

 tire visceral lymphatic system is in the great veins, or ducts of 

 Cuvier, on either side of the heart. 



From each of the great lymph sinuses, along the oesopha- 

 gus, there extend little bay-like prolongations which open 

 into the venous trunks, as just mentioned. In one specimen 

 three of these openings were seen on each side ; possibly there 

 were still other smaller ones. The mechanism of the valve- 

 like structures which close these orifices needs further study. 

 The lymph sinuses were repeatedly filled with air, yet but 

 little, sometimes none, v/as seen to escape into the veins ; 

 liquids seemed to pass somewhat more readily. It was found 

 practically impossible to pass a beaded bristle from the lymph 

 sinus into the veins, or the opposite, although the orifice is 

 much larger than the bristle. When the sinuses are dis- 

 tended with air, the thin walls around the openings form 

 slight, rounded swellings, which project into the lumen of the 

 blood-vessel. Immediately around the orifice the walls are 

 somewhat thickened, and as nearly as could be made out 

 these thickened portions over-lap each other, in somewhat the 

 same way as would result if a slit were made in a hollow 

 sphere and one edge drawn over the other. This over- 

 lapping of the edges of the orifice would account for the difii- 

 culty of passing a bristle through the opening. 



THE ENTERIC EPITHELIUM. 



The enteric epithelium of this most teleosteoid (in appear- 

 ance) of Ganoids, as it has been called, exhibits certain mor- 

 phological features peculiar, so far as at present known, to the 

 group Ganoidei. The buccal cavity is covered by a stratified 

 epithelium ; the superficial layers are flattened while the 

 deeper lying cells are more nearly columnar ; the intermediate 

 cells gradually merge from the one into the other as is com- 

 mon with this kind of epithelium. At irregular intervals the 

 epithelium is pierced by large conical or dome-shaped struct- 

 ures which project to the free surface. These doubtless cor- 

 respond to those structures which according to Wiedersheim 



