OF HYOMQSCHUS AQUATICUS. 457 
deep surface of the mucous membrane and its glands with the mus- 
cular coat. This band in all probability was the muscularis mucose. 
In Hyomoschus, as in other animals possessing a diffused placenta, the 
uterine glands have no relation, as regards numbers or termination, to‘ 
the crypts. The crypts are infinitely more numerous than the glands, 
and are not to be regarded as formed by dilatation of their mouths, 
but are new formations during pregnancy, due to hypertrophy and 
folding of the mucous membrane so as closely to adapt it to the irre- 
gular villous surface of the foetal chorion. 
The chorion extended from the tip of the left uterine cornu, 
through the corpus uteri, to the tip of the right uterine cornu. The 
left horn of the chorion, which contained the foetus, was longer and 
much more capacious than the right horn. The tip of each horn of 
the chorion was in close relation to the orifice of each Fallopian tube ; 
and close to the tip the free surface of the chorion was over a very 
limited area smooth and non-villous. That part of the chorion situated 
in the corpus uteri, immediately opposite the os uteri, presented a cir- 
cular non-villous surface about the size of a shilling. This surface, 
though without villi, was folded so as to adapt it to the corresponding 
folds of the uterine mucosa in the same locality. A portion of the 
chorion corresponding to the more convex part of the gravid uterine Page 685. 
cornu was thinly covered with villi, and, indeed, in one or two very 
_ limited areas was non-villous—these bare or thinly covered patches 
being in contact with those portions of the uterine mucosa (already 
described) where the crypts are either shallow or absent. In all other 
localities the free surface of the chorion was as thickly studded with 
villi as the uterine mucosa was with crypts; so that it furnished an 
excellent and characteristic example of a diffused placenta. In the 
absence of villi from those parts of the chorion which were situated in 
relation to the three uterine orifices, 7.c., the os uteri and the two 
Fallopian tubes, the chorion of Hyomoschus corresponded with what 
one of us has elsewhere described in Orca, the Narwhal and the Mare. 
The villi were arranged in small tufts, separated from each other 
by very narrow intervals. The tufts varied in size; and the villi of 
which they were composed were short and branched, usually in the 
form of filamentous processes. The basal substance of each villus 
and of the chorion itself consisted of a delicate corpusculated con- 
nective tissue. The epithelium on the free surface of the chorion 
was partly shed ; but considerable patches of it were seen in many 
localities. 
The amnion formed a capacious bag, which extended to within 
half an inch of the tip of the left horn of the chorion. It occupied 
the rest of this horn and the part of the chorion situated in the 
corpus uteri, but did not extend into the right horn of the chorion. 
