AND ITS CONNEXION WITH THE UTERUS. 
65 
uterus, ending in a well-defined and smooth semicircular margin, the central 
part adhering to, and being apparently continuous with, the decidua. 
In the course of this dissection I observed that where the veins of different 
planes communicated with each other, the central portion of the parietes of the 
superficial vein invariably projected in a semilunar form into the deeper-seated 
one ; and where (as was frequently the case, and especially at the point of ter- 
mination on the inner surface) two or even three veins communicated with a 
deeper-seated one at the same point, these semilunar edges decussated each 
other so as to allow only a very small part of the deep-seated vein to be seen. 
I need not observe to you how admirably this structure is adapted to ensure 
the effect of arresting the current of blood through these passages, upon the 
contraction of the fibres with which they are everywhere surrounded. 
On another portion of the same uterus and placenta, (which were removed 
from a woman who died at about the fifth month of utero-gestation,) I com- 
menced the examination under water by turning the placenta and deciduous 
membrane from the inner surface of the uterus. In this way the small tortuous 
arteries that enter the deciduous membrane were readily distinguishable, though 
not filled with injected matter ; and as it was an object to avoid unnecessary 
force in the process of separation, they were cut through, though they are 
easily torn from the decidua. But with respect to the veins, they invariably 
presented the same appearances as were noticed in the first dissection, termi- 
nating in open semicircular orifices, which are closed by the apposition of the 
deciduous membrane and placenta. This membrane is, however, certainly 
thinner opposite these orifices than elsewhere ; and in some places appeared 
to be wanting, or adhering to the vein was torn up with it ; but in these cases 
the minute vessels of the placenta only appeared, and never any indication of 
a vascular trunk or cell commensurate with the size of the vein whose terminal 
aperture had been lifted up from the part. 
The preparation which accompanies this letter shows the termination of a 
vein on the inner surface of the uterus, and an artery of the decidua cut through, 
with the corresponding appearances on the surface of the placenta, — also the 
valvular mode in which the veins communicate together in the substance of 
the uterus. 
I remain yours very truly, 
Richard Owen. 
mdcccxxxii. K 
