1878.] THE PLACENTA OF HYOMOSCHUS AQUATICUS. 683 



are blocked up by a whitish viscid mucus. Behind the most poste- 

 rior transverse constriction the vagina undergoes a considerable dila- 

 tation, and the mucous lining exhibits faint longitudinal folds. 



The uterine walls are slightly thinner than those of the human 

 stomach. The cavity of the two cornua and of the corpus uteri is 

 lined by a well-defined mucous membrane, from which the foetal 

 chorion can readily be separated. This mucous membraue forms 

 the maternal portion of the diffused placenta characteristic of Hyo- 

 moschus. The mucosa of both cornua is not elevated into folds, 

 except in close proximity to the openings of the corresponding Fal- 

 lopian tubes ; and the mucous lining of the corpus uteri is longitudi- 

 nally folded only in proximity to the os uteri. The free surface of 

 the mucous membrane, both in the cornua and corpus and on both 

 surfaces of the septum uteri, is soft and velvety and pitted with 

 multitudes of minute depressions just visible to the naked eye. These 

 depressions are the crypts in which the villi of the chorion are lodged 

 when the chorion is in situ. The crypts are distributed with almost 

 equal regularity over the surface of the mucosa in the several divi- 

 sions of the uterus ; but on the more convex part of the impregnated 

 left cornu the mucosa is not quite so thick, so that the crypts are 

 shallower, and over a limited area- the free surface of the mucous 

 membrane is almost, if not quite, free from crypts. We did not, 

 however, see any depressed circumscribed smooth areas surrounded 

 by crypts such as one of us has. described elsewhere 1 in the Pig and 

 Lemurs, or polygonal areas occupied by crypts and bounded by ridges 

 free from crypts, such as are to be seen in the gravid uterus of the 

 mare. In the regular diffusion of the crypts over the surface of the 

 mucosa, the gravid uterus of Hyomoschus much more closely re- 

 sembled what has been described in Orea gladiator" than it did the 

 uterine mucosa of the Pig, Mare, and Lemurs. 



We then carefully stripped portions of the mucous membrane off 

 the subjacent muscular coat, and soaked them in glycerine for some 

 days, in order to render the membrane as translucent as possible. 

 When the mucosa thus prepared was examined microscopically, the 

 openings of the uterine glands on the surface of the membrane could 

 be seen. Sometimes these openings were found on the slender raised 

 folds of mucosa separating adjacent crypts from each other ; at other 

 times they opened into the crypts, and at other times on smoother 

 portions of the membrane where the crypts were shallower or almost 

 absent ; but in no case were the mouths of the glands specially 

 localized in smooth circumscribed areas of the mucosa, as is the case 

 in the Pig and in the Lemurs. The gland-orifices were directed 

 obliquely to the plane of the free surface of the membrane ; and it 

 was not uncommon to see an epithelial plug projecting through the 

 mouth. 



Additional views of the relation of the glands to the crypts were 

 obtained by making vertical sections through the mucosa. This 



1 Turner, Lectures " On the Comparative Anatomy of the Placenta," Edin- 

 burgh, 1876, and Trans. Roy. Soc. London, 1876. 



2 Turner, Trans. Eov. Soc. Edinburgh, 1871. 



44* 



