272 PROCEEDINGS OF THE CANADIAN INSTITUTE. 
usually observed in fishes. In some respects these peculiarities may 
be considered as due to a derivation accompanied. by little dif- 
ferentiation from structures which were probably present in the 
primitive type of fishes. 
Of these, pouch-like deverticula of the epithelium in the cesophageal 
portion of the fore-gut in the genera named, are in their inflated 
portion wholly lined by flattened, almost squamous, epithelial cells, 
each with a flattened nucleus and a quantity of clear protoplasm. 
The cells in the neck of the pouch are cylindrical, strongly ciliated, 
and but little differentiated from the common epithelial cells of the 
cesophageal mucous membrane. The neck varies much in diameter 
and length, being as a rule about half the diameter of the inflated 
portion. Pouches of this description are most highly developed in 
Acipenser, least so in Lepidosteus. It is impossible to say at present 
what their function is, but I believe that it is transudatory. They 
are not glandular in the present definite acceptation of the word, 
and they cannot be for the purpose of absorbing digested food 
matter, since they are too far in front of the seat of digestive 
changes. I have seen no description of like structures as occurring 
in any other vertebrate. 
The csophageal portion of the fore-gut in Amia and Acapenser 
possesses glands similar to those found in the stomach in the same 
genera, and which undoubtedly secrete pepsin. In this same part of 
the fore-gut there are gland tubules which, in the cells lining them, 
show all the degrees of differentiation from a simple epithelial erypt 
to a fully formed peptic gland tubule. In the same two general 
cesophagus and stomach act together as a digestive structure, both 
being provided with peptic glands. In Acipenser the part of the 
fore-gut which has hitherto been termed the cesophagus, possesses 
taste-buds in large numbers and cannot, therefore, be rightly so 
named. The part following it, and terminating behind the mouth of 
the air duct, must, from the histological structure, be considered as 
the cesophagus. 
The lining epithelium of the cesophagus in Acipenser and Lepidos- 
teus, and that in cesophagus and stomach in Ama, is ciliated. In 
all, the stomach possesses peptic glands of the type usual in fishes. 
In Acipenser, glands of this character have been previously over- 
looked, Leydig having described as such the ordinary epithelial 
insinkings, or crypts, into which the true glands open. 
