SHAPE AND STRUCTURE OF ALIMENTARY VISCERA OF PORPOISE. 323 



the proximal limb was rather shorter than the distal one. A small amount of constriction 

 was observed at the angle of the A, while at its termination it was bent slightly for- 

 wards. It would be possible to describe this segment of the stomach as two chambers, 

 but that seems to be uncalled for, in view of the fact that the microscopic characters of 

 its mucous membrane did not, in any special manner, differ from those detailed for the 

 third compartment. Indeed, there is reason to believe that this entire segment is, in 

 reality, one chamber of nearly uniform cylindrical appearance, capable of being divided 

 into a larger or smaller number of subdivisions by means of septa or circular con- 

 strictions more or less pronounced. It is this chamber which is so frequently divided 

 in the narwhal. They might very well correspond to the pyloric half of the human 

 stomach subdivided by constrictions. The proximal limb of the A-shaped compartment 

 was situated in front of the third chamber and in close apposition with the lesser 

 curvature of the second, to which it was intimately connected by direct prolongations of 

 the peritoneum upon their free surfaces. The great omentum was also continued into 

 the angle formed by the limbs of the V. Like the preceding compartment, it was empty. 

 From its inlet to the slight constriction at the angle of the V measured three and a half 

 inches (9 cms.) in length by one and a half (38 mms.) in width. The general form of 

 this segment of the chamber was an elongated oval. 



Its walls, as regards thickness, were similar to those of the preceding chamber. The 

 mucous membrane was pale, showing only a faint amount of rugosity ; thereby indicating 

 that it did not require to undergo much distension. At intervals pin-point depressions 

 like those already noted in the preceding chamber were observed. At the point of the 

 V — i.e., at the acute angle — there was a certain narrowing of the lumen which might be 

 described as constriction, or might be referred to the mere acute bending. The micro- 

 scopic features of the mucous membrane did not differ in any marked way from those 

 already described in connection with the third compartment, but the tubules were 

 probably rather shorter, and the mucous membrane slightly thinner. 



The distal limb of the inverted V extended to the pylorus. It virtually formed a 

 cylindrical tube measuring about five inches (13 cms.) in length, and directed backwards 

 and to the right. Within one inch (2 '5 cms.) of the pylorus it underwent a slight dilatation 

 on its hinder aspect, forming an Antrum pylori. At the same time it turned forwards with 

 considerable abruptness, to end at the pylorus. Along its anterior and somewhat concave 

 aspect it afforded attachment for the gastro-hepatic omentum. Between the laminse of 

 this omentum, masses of lymphatic gland were found towards its left end, and the head 

 of the pancreas occupied a similar position in relation to the pylorus at the right end 



The mucous membrane was very slightly rugose, and presented numerous pin-hole 

 depressions, each of which, as in the places already mentioned, was surrounded by a 

 slightly raised ring of the mucous membrane. Microscopically the mucous membrane 

 did not present any variation upon what has been stated in connection with the last two 

 compartments (PI. III. figs. 7a and b). Apparently the pin-hole depressions may be 

 associated with the nodules of lymphoid tissue which are everywhere embedded in the 



