THE PHARYNGEAL TEETH OF FISHES. 193 



growing in two rows. This fish, like the last, has only three 

 gill arches. The back of the gullet is divided into three distinct 

 parts. In the upper part, on its outer corners, there are horny 

 corrugations arranged more or less vertically (fig. III., 3). 

 The two lower sections stretch as two bands across the pharynx. 

 The floor of the gullet is covered with mucous membrane, 

 studded with papillae. 



GONORHYNCHIDJE. 



Gonorhynchus greyi has fifteen long horny gill-rakers on the 

 first cerato-hypobranchial with twelve on the first epibranchial 

 arch ; the longest about f- of the gill-filament below it. The 

 other arches have many similar but shorter gill-rakers that lie 

 across the gill slits and make a very perfect filter. There are no 

 pharyngeal teeth, upper or lower. There is a group of strong 

 conical teeth at the root of the tongue, which engage against 

 two plates of similar teeth on the pterygoid bones. These seem 

 adequate to perform any function that the absent pharyngeal 

 teeth would perform. An " uvula " like body, a lobe of mucous 

 membrane, hangs down from the roof of the palate in front of 

 the pterygoid plates ; it is stiff, but seemingly admits of folding 

 backwards. 



Zool. 4th ser., vol. XX., May, 1916. 



