PEOF. W. TUENEE ON THE PLACENTATION OF THE LEMUES. 
577 
as far as the head of the fetus, but did not pass into the short diverticulum of the 
chorion which occupied the non-gravid horn. Opposite the abdominal aspect of the 
fetus, where the umbilical vessels passed to the chorion, the outer wall of the sac of 
the allantois was reflected on to the inner surface of the chorion ; and along a line 
opposite the back and head of the fetus the allantoic membrane was again reflected on 
to the outer surface of the amnion, so as to form the inner wall of the sac of the 
allantois. The sac of the allantois was thus divided into two almost equal parts, one 
corresponding to each lateral aspect of the embryo ; but as the line of reflection opposite 
the abdominal aspect was not equal to the length of the sac, the two halves on 
opposite sides freely communicated with each other. The amnion formed a well-defined 
bag enclosing the fetus, coequal in length with the sac of the allantois, and, like it, 
not extending into the short diverticulum of the non-gravid cornu. 
Diagram of the arrangement of the foetal membranes of Lemur rufipes, as seen in 
transverse section through the embryo. 
33. Embryo. Ch. Chorion, with villi and non-villous patches. 
Al. Sac of allantois. Am. Sac of amnion. The dotted line represents the amnion. 
The fetus was well developed, and measured between 5 and 6 inches from the tip of 
the nose to the root of the tail. The head, instead of being bent forward under the 
thorax, was twisted round, so that the lower jaw rested on the back. The tail, 4 inches 
long, was curved under the belly. The hind limbs were flexed at the hip, knee, and 
ankle-joints; the joints of the fore limbs were also bent. The skin was well haired, 
and the nails were developed on the digits. 
When the uterus of A, the least developed specimen, was opened into by an incision 
along the posterior wall, the non-gravid cornu was seen to communicate with the corpus 
uteri 1x2 inch from the os uteri. The corpus uteri, for \ an inch beyond the os, was a 
narrow tube, in which the mucous membrane was longitudinally folded as in the non- 
MDCCCLXXVI. 4 L 
