76 PROFESSOR TURNER ON THE PLACENTATION OF THE SLOTHS. 
The amnion was closely adherent to the inner surface of the non-placental 
part of the chorion (fig. 3, am). The two membranes could be separated 
by tearing through a thin layer of very delicate intermediate areolar tissue. 
The amnion was prolonged over the inner face of the placenta, and at the place 
of attachment of the funis was reflected upon the umbilical cord, which it 
invested, and by which it was conducted to the abdominal aspect of the foetus. 
The inner free surface of the amnion was smooth and serous, although there 
was an absence of liquor amnii. This membrane was non-vascular, and con- 
trasted, therefore, with the vascular chorion. 
The placenta was subdivided into about thirty lobes or “ cotyledons,” but to 
prevent any possibility of misconception as to their nature, I shall in the course 
of my description speak of them not as “cotyledons” but as lobes. These 
lobes were not scattered over the surface of the chorion, as the cotyledons are in 
the Ruminants, but were more or less closely aggregated together. Not un- 
frequently they were in, or almost in, contact with each other by their margins ; 
but sometimes narrow strips of chorion separated them from each other. A 
somewhat broader strip of non-placental chorion, continuous with that which lay 
adjacent to the os uteri, passed obliquely between the lobes forming the anterior 
part of the placenta, almost up to the fundus, so that the organ was imperfectly 
subdivided by it into right and left lateral halves (fig. 3, ch’). The umbilical cord, 
54 inches long, joined the chorion about the centre of this strip, opposite the 
middle of the inferior wall of the uterus. Its vessels, consisting of a vein and two 
arteries, branched and radiated outwards, to ramify on the chorionic surface of 
the lobes prior to entering their substance. Owing to the separation between the 
lobes being much better marked than in the human placenta, so compact an 
organ was not formed as is met with in the human subject. 
The lobes were irregularly discoidal in shape, and varied considerably in size. 
The largest had a long diameter of 2 inches, and a thickness of ;4jths inch, whilst 
the smallest were not more than half an inch in diameter. The greater 
number possessed distinct rounded margins, so that they had a well-defined 
individuality ; but in a few instances some of the lobes were partially blended 
with each other by the fusion of their adjacent margins. The chorionic surface 
of the lobes was convex, and projected towards the interior of the ovum, after 
the manner described and figured by Carus in B. tridactylus. By the oppo- 
site surface the lobes were attached to the inner wall of the uterus, in a manner 
to be immediately described. 
The non-placental area of the chorion lay free in the hinder part of the 
uterine cavity. It was in contact with, but not adherent to, the uterine mucous 
membrane. When raised from its position, its uterine surface was seen to be 
partially invested by a thin yellowish-brown layer, which could be easily peeled 
off, and which became continuous with the mucous membrane, covering the 


