96 PROFESSOR TURNER ON THE PLACENTATION OF THE SLOTHS. 
In the new world Monkeys the placenta consists of a single disc-shaped 
organ, which is probably also the case in the anthropomorphous apes, though 
in the tailed apes of the old world, as HuNTER and BrescHet’s observations 
have sufficiently shown,* the placenta is subdivided into two large lobes by a 
greater or less interval. JoHNn Hunter has pointed out that each of these large 
lobes is made up of smaller ones, united closely at their edges—a feature which 
BreESCcHET also has confirmed (op. cit. p. 445). The subdivision of the placenta 
in these monkeys into two parts is interesting in connection with the arrange- 
ment seen in the sloth’s placenta, where a partial separation into a right and left 
lateral half was found, each of which in its turn consisted of smaller lobes. But 
though the form of the placenta, the existence of a decidua, the absence of the 
sac of the allantois, the absence, or at least the rudimentary condition, of the um- 
bilical vesicle, + the arrangement of the amnion, and the comparative length of 
the umbilical cord, have all been determined in the quadrumana, and correspond 
in most particulars with what I have described in the sloth, yet there is, unfor- 
tunately, a want of precise information on the arrangement of the maternal 
blood-vessels, and the condition of the utricular glands in the former group of 
animals. JoHN HuNTER, indeed, says, veins or sinuses were placed in the fissures 
between the lobes, which received the blood laterally from the lobes, and 
that the substance of the placenta seemed to be “cellular,” as in the human 
subject. Dr Rotieston, from the examination of a spirit-preserved placenta of 
Macacus nemestrinus (op. cit. p. 301), obviously inclines to the view that in it 
intraplacental maternal sinuses existed, though he points out that, from the age 
of the specimen, the examination was not so satisfactory as he could have 
desired. Prof. Erco.ant states, { from an examination of a specimen preserved in 
spirit, of the placenta of Cercopithecus sabaeus, that in this monkey the placenta in 
its microscopic characters, as well external as internal, does not present any 
difference from that of woman; so much alike are they, that as he had just 
described the human placenta, he did not think it necessary to go into the 
details of structure in the ape. He does mention, however, that the intra- 
placental lacunee in Cercopithecus, which contain the maternal blood, are smaller 
than in woman; and that on the uterine face of the placenta are manifest 
traces of serotina, which is continued on to the foetal villi forming the external 
membrane, or the walls of ErRcoLAnt’s glandular organ. As he had stated on p. 36 
that he had never seen utricular glands in the human placenta, we must 
* Figures of the placenta in the Quadrumana, or descriptions of its naked-eye characters, will be 
found in Joun Huwnrer’s Collected Works, iv. 71; Plates xxxv., xxxvi., and fig. 2, xxxiv.; in 
Rupotpexrs Memoir, “ Ueber den Embryo der Affen,” already quoted ; in Brescuet’s important Essay 
in Mémoires de I’ Institut, 1845, xix. ; and in Ownn’s Comparative Anatomy of Vertebrates, i. 747, 
in which volume it is mentioned that the pregnant monkey, dissected by Hunter, the name of which 
that anatomist had omitted to give, was a specimen of Macacus rhesus. 
+ Compare Brescuet’s description of Simia Sabaea with that of Simia nasua, pp. 444, 470. 
+ Mem. dell’ Acad. di Bologna, 1870, p. 53. 

