PLATANISTA. 491 



In the umbilical expansion of this bare tract, there is a small cul de sac with 

 a crescentic orifice (fig. 1, c) . Moreover, near its termination on the right horn, a 

 small pedunculated corpuscle (fig. l,p.) of the same character as the amnionic 

 corpuscles of the cord and allantois occurs, with a small pear-shaped tubercle at its 

 base. Eacing towards the pole, and from the base of the peduncle of the corpuscle, 

 there is a raised, somewhat monihf orm and tubular-looking fold which can be traced 

 along the middle of the bare tract to near its left termination. 



As I did not succeed in injecting the villi of the chorion (PL XXXVII, fig. 12), 

 I cannot give any idea of their true form when charged with blood, and I can say 

 nothing regarding the arrangement of the blood vessels in them. 



Memhrana intermedia. — Even when the membranes are comparatively dry, a 

 thin delicate membrane can be demonstrated to exist between the chorion and 

 amnion, between the amnion and allantois, and between the allantois and chorion. 

 But when they have been placed in water for about an hour, this structure in the 

 right horn of the chorion swells up into a gelatinous mass, and it also assumes the same 

 character, but in a more limited degree, between the chorion and amnion in the left 

 horn. When the amnion is stripped off the chorion in the last mentioned locality, 

 it has a gelatinous feeling on its outside, which is due to the presence of this mem- 

 brane, which is also apt in every part of its extent to drag the vessels of the chorion 

 along with it. Between the amnion and allantois the membrane does not tend to 

 swell up on soaking, but preserves an extremely fine character. 



Amnion. — This is entirely confined to the left horn of the chorion and can be 

 easily separated from off the allantois over which it has only a limited distribution. It 

 does not follow the allantois into the right horn of the chorion, nor does it invest the 

 portion of the chorion depending into the cavity of the body of the uterus. It is 

 closely related to the membrana intermedia. Towards the left pole its surface which 

 covers the allantois is studded over with small corpuscles and evidently identical with 

 the corpuscles of the amnion of Orca described by Turner^ and having the same 

 relation to the amnion. Towards the left of the funis the same surface of this 

 membrane has a broad transverse area devoid of these corpuscles, but further to the 

 right and towards the middle of the allantoic surface these corpuscles are again 

 numerous. Some of them are extremely minute and scarcely visible to the naked 

 eye, and they are confined to the allantoic surface of the amnion. These corpuscu- 

 lated surfaces of the amnion are also studded over, in certain parts in great profusion, 

 with minute sessile grey papilla-like structures, which give a rough feeling to the 

 membrane. Corpuscle-like bodies, stalked and sessile, also occur on the amnion as 

 it sheathes the cord (PI. XXXI, fig. 1, c). 



The first mentioned bodies of the amnion, which vary in size from 0*04 inch 

 to 0"70 inch, are nearly aU pedunculated, and appear to be structurally identical 

 with the long pedunculated and sessile bodies which stud the amnionic covering of 

 the cord. The microscopic structure of these bodies I have not been able to satis- 

 factorily determine, as all those which I have examined had been long preserved in 



^ Turner: Lectures on Placent., p. 23. 



