90 PROFESSOR TURNER ON THE PLACENTATION OF THE SLOTHS. 
organ possessed considerable thickness; and although the younger MILNE 
Epwarps could not, from the condition of his specimen, speak positively of the 
presence of a decidua, the thick spongy character of the organ with the compact 
arrangement of the villi points rather to a deciduate than a non-deciduate 
structure. 
In the Tardigrada, the Dasypodide, and the Orycteropodide, we have 
evidence then that the placenta is deciduate, and composed of one or more disc- 
shaped lobes. Inthe Myrmecophagide the evidence is not so complete, though 
I think it inclines in favour of the deciduate nature of the placenta. 
But when we turn to the Scaly Ant-eaters we find a placenta of a very dif- 
ferent character. Some years ago Dr SHARPEY examined the gravid uterus of 
a Manis, which, from the size of the foetus, was presumably near the full time. 
He observed several most important features in the arrangement and structure 
of the placenta, which he communicated to Professor Hux.ey, who incorporated 
them in his “ Elements of Comparative Anatomy.”* ‘“ The surface of the chorion 
is covered with fine reticulating ridges, interrupted here and there by round 
bald spots, giving it an alveolar aspect, something like the inside of the human 
gall bladder, but finer. The inner surface of the uterus exhibits fine low ridges 
or villi not reticulating quite so much. The chorion presents a band free from 
villi, running longitudinally along its concavity, and there is a corresponding 
bald space on the surface of the uterus. The ridges of the chorion start from 
the margins of the bald stripe, and run round the ovum. The umbilical vesicle 
is fusiform.” 
In a letter to me, in reply to a request for further information about this 
specimen, Dr SHArPEy states that it had been in spirit before coming into his 
possession, and that the substance of the uterus and the tissues of the embryo 
were brown and fragile. An injection, both of the uterus and membranes, was 
attempted, but, from the condition of the parts, was unsuccessful. The eleva- 
tions on the chorion corresponded to the finely-corrugated inner surface of the 
uterus. “I turned off the chorion like an everted stocking, and got the 
arrangement of the allantois, fusiform umbilical vesicle, omphalo-mesenteric 
and umbilical vessels. The ramifications of the umbilical vessels extended 
generally over the inner surface of the chorion, and were lifted off with it from 
the receptacular part of the allantois, which was very extensive, and passed into 
the diverticula of the chorion. The uterine glands were abundant and easily 
seen, but I could never distinctly trace their orifices ; 1t seemed to me as if the 
ducts opened not abruptly, but gradually and funnel-like among the placental 
ruge. I think you found this condition in the whale.” 
I have not only to express my thanks to Dr SHarpey for this additional in- 
formation, but to state that with great liberality he has allowed me to examine 
* Pp. 112. London, 1864. 
