PROFESSOR TURNER ON THE PLACENTATION OF THE SLOTHS. 89 
to Classification,” * based on the examination of aspecimen in the stores of the 
Royal College of Surgeons, London, that in this genus the placenta is discoidal 
and deciduate. 
Of the Hairy Ant-eaters, A. F. J. C. Maver statest that in Myrmecophaga 
(Cyclothurus) didactyla a single orificium uteri exists, and in the gravid state 
the uterus and vagina are blended into a common cavity, and form a round mem- 
branous sac. The foetus in the specimen he examined was well developed and 
strongly haired, with the head presenting. The placenta was a thick roundish 
cake (Kuchen), and lay to the right in a special pouch of the uterus. The chorion 
and amnion were distinct, but the erythrois and allantois could not be dis- 
tinguished in the torn membranes. Prof. WELCKER, in his Memoir already 
quoted, incidentally mentions that in M. didactyla the amnion and chorion 
circumscribe in the usual way the border of a fungiform (pilz-/ormig) placenta. 
The elder MitnE Epwarps states { that he has found in M. didactyla a discoid 
placenta, but composed at its borders of small branched tufts: it did not 
appear to be united to the uterus by a decidua. His son, M. ALpHoNsE MILNE 
Epwarps, described only last year§ a placenta of ZTamandua tetradactyla, 
which had been hardened in spirit for some years before it came into his 
possession. It occupied the larger part of the surface of the ovum, and was 
not composed of simple villosities like the placenta of the Pachydermata, but 
of vascular very compact vegetations. Its central part was thick and spongy ; 
its borders well defined, with a smooth chorion beyond them. The vascular 
vegetations, he says,.do not apparently resemble the reticulated folds and alveoli 
seen by Dr SHarpey in Manis. Some débris of uterine tissue indicated the 
presence of a decidua, but he could not speak positively on the subject. The 
placenta is unilobed, dome-like in the mode in which it is set on the chorion, 
and is named by Mitne Epwarps placenta discoidal envahissant. The surface 
of the placenta next the embryo did not possess the projections seen by Carus 
in Bradypus, or by myself in Cholepus, but was smooth. No trace of an 
allantois was found. 
From the above descriptions it is clear that in the hairy ant-eaters the 
placenta is not diffused over the whole surface of the ovum, but is localised in 
a particular area. From Mine Epwarps’ figure the proportion of chorion 
occupied by the placenta is about equal to what I have seen in Cholapus, but 
the organ is not, as in the latter animal and in Bradypus, subdivided into lobes. 
From the expressions Kuchen employed by Mayen, pilz-férmig by WELCKER, 
discoid and spongy by MiILne Epwarps, pére et jils, it is also clear that the 
* P. 104. London, 1869. 
t Analecten fiir Vergleich. Anatomie. Zweite Sammlung, p. 54. Bonn, 1839. 
t Legons sur la Physiologie, ix. part 2, p. 563, note. Paris, 1870. 
§ Annales des Sciences Naturelles,xv. 1872. 
