278 PROFESSOR TURNER ON THE 
outer end of this cornu. The presence of a large zonary placenta was then 
recognised, and the outer envelope of the foetus, the chorion, was seen to extend 
from the orifice of the right Fallopian tube as far as the extremity of this cornu, 
close up to the os uteriinternum. A small quantity of reddish-brown fluid, obvi- 
ously situated between the mucous membrane of the uterus and the outermost 
foetal envelope, escaped when the wall of the uterus was cut through. The 
foetus lay within its membranes with its snout directed towards the os internum, 
its tail and hind flippers towards the free end of the horn, its back in relation 
to the anterior convex border of the uterine cornu, and its abdominal aspect 
opposite the posterior concave border. The foetal membranes were then punc- 
tured to allow of the escape of a quantity of reddish allantoic fluid, and on 
slitting them up still further, the foetus, with its umbilical cord, a little more 
than two inches in length, was exposed. The umbilical vein was opened into, 
and a quantity of a transparent blue injection was thrown into the foetal part 
of the placenta. Into one of the umbilical arteries some red injection was then 
passed. The cord was now cut through, and the foetus removed. 
The zonary placenta formed a broad belt, 0°3 to 0-4 inch in thickness, which lay 
about midway between the tip of the gravid horn and the septum between it and 
the left cornu. Its transverse diameter was not uniform, for it measured 9 inches 
in breadth opposite the anterior convex surface of the horn, and not more than 
4 inches at the concave posterior surface. Each lateral border of the placenta 
was free, but continuous with the non-placental part of the chorion. Its 
uterine surface next this free border, for a breadth of from 2 inch to 14 inch, 
varying in different localities, was not adherent to the uterine wall like the great 
mass of the placenta, but was covered by a prolongation of the mucous lining 
of the non-placental part of the uterus, which was reflected on to it so as to 
form a distinct band of decidua reflexa, which was not, however, continued on 
to the non-placental part of the chorion. This reflected decidua was delicate, 
and tore down so readily, more especially at its free edge, that portions were 
stripped away in the act of handling the placenta during its examination. In 
this manner the foetal villi were exposed, and formed a fringe around the free ~ 
border of the placenta. Except in the placental area, the outer surface of the 
chorion was perfectly smooth. 
The foetal membranes and placenta were then everted, in order to obtain a 
more complete view of the general disposition of the membranes and of the 
inner face of the placenta. 
The sac of the allantois was co-equal in length with the chorion, to the 
inner surface of which its membrane was so closely adherent that it was diffi- 
cult to separate it from the chorion without tearing one or other of the two 
membranes. The allantois was prolonged over the inner face of the placenta, 
except at the part opposite the abdominal aspect of the foetus, where the 


