72 PROFESSOR TURNER ON THE PLACENTATION OF THE SLOTHS. 
is a longish rounded placenta, in which, according to Carus and Rupo.pai, 
distinct cotyledons, which however lie near each other, can be recognised.” 
M. H. Mitne-Epwarps in his memoir Sw la Classification Naturelle des Ani- 
mauz* constructs a Table in which he places the Edentata amongst the mammals 
with diffused and cotyledonary placentze. In the text of his valuable Legons sur la 
Physiologie et VAnatomie comparée, he statest that the structure of the placenta 
of the Edentata is so very imperfectly known, that it is needless to discuss it ; 
but in some comments in a foot-note, he remarks that Carus says nothing 
of the nature of the cotyledons of the sloth’s placenta to make us think that 
their structure is analogous to that of the cotyledons of the Ruminant: “as 
far as one can judge from his figure, they appear to me rather to resemble 
the placenta of a monkey, but instead of being bilobed merely, to be subdivided 
into a considerable number of lobular portions.” 
Professor OWEN remarks{ that the placenta of the phytophagous sloth 
(Bradypus) is almost as much subdivided as in the smaller Ruminants; but 
the true affinities of the sloth would be violated by transferring it to the 
Ruminantia on the score of mere accordance of placental form. Subsequently 
in his “Treatise on the Comparative Anatomy of Vertebrates,”§ after referring 
to Carus’ description of the placenta of Bradypus, he states that the placental 
cotyledons have no corresponding partial thickenings of the lining substance 
of the uterus as in the Ruminants, but “their flattened outer surface applied, 
with the uniting layer of chorion, to the inner surface of the uterus, may receive 
therefrom a medium of ramification of maternal vessels, answering to a decidua 
serotina. The probability indeed is that maternal deciduous substance is inter- 
blended with such allantoic lobules of the sloth, as is the case with the single 
thin oblong placental disc in Dasypus.” Professor HUuXLEY again, in his 
published Lectures, remarks,|| “among the Edentata the sloths have pre- 
sented a cotyledonary placenta;” and after relating some observations by Dr 
SHARPEY on the placental structure of Manis, which show it to be a non- 
deciduate placenta, he states, ‘and the cotyledonary form of that of the sloths 
leads me to entertain little doubt that it belongs to the same category.” 
Also in his “ Introduction to Classification” he says, “In the Edentata the 
placentation appears to vary, being diffuse and non-deciduate in Manis, cotyle- 
donous (and non-deciduate ?) in Bradypus, and discoidal and deciduate in 
Orycteropus: but further investigation is needed before such variations can be 
* Annales des Sciences Naturelles, p. 98, vol. i. 1844. 
f Volaxsp.D6o. | Pans 1870, 
t Philosophical Transactions, 1857, p. 352. 
§ Vol. iii. p. 731. 
|| Medical Times and Gazette, May 30, 1863, p. 555, and Elements of Comparative Anatomy, 
p. 111, 1864. 
{ London, 1869, p. 104. 
