252 



Dr. J. D. F. Gilchrist on the 



markedly from the pharyngeal teeth, which form a small 

 part of the inner lining of the sac at its anterior end. They 

 bear a close resemblance to the gill-rakers, which iu tiiis hsii 

 are well developed. One of these, which was cut and treated 

 in the same way, showed the same structure. It was 2"89 mm. 

 in length ; the spines were not, however, slightly curved, as 

 in tlie oesophageal teeth. The conclusion arrived at is that, 

 iu this case, some of the teeth of the oesophageal sacs are 

 teeth of the upper pharyngeals, most of them, however, being 

 liomologous with gill-rakers probably arising as an extension 

 backwards of the epithelium of the last gill-arch. 



Stromateus capensis. 



The oesophageal sacs in this species form an almost 

 spherical mass, about 17 mm. in diameter in a fish 200 nnn. 



Fig. 2. 



One of the toolh-likc processes of the a-sophageal sacs of 

 Stromateus capensis. Magnification the sauio as Fig. 1. 



in length, or one and a half times the diameter of the eye. 

 It is nearer the branchial region than in the last case, and is 



