PLACENTAL STRUCTURES OF THE TENREC. 299 



site is on the mesometrial border, and in all also, and not merely in the Rabbit', does 

 the chorion receive a vascular supply from the omphalo-mesenteric as well as from the 

 umbilical arteries. In all Rodents that I have examined at the time of their birth the 

 omphalo-mesenteric vessels were persistent. In this point they agree with the Carnivora ; 

 and in that of these vessels being supplied to the chorion, the Vampire resembles them. 



SimiadcB. 

 A female Pig-tailed Monkey {Macacus nemestrinus) having died after giving birth to 

 a foetus, and having had one of its two morbidly adherent placentae removed by artificial 

 means before its death, the maternal vessels were injected with a red, and the foetal with 

 a chrome-yellow injection. One of the two placentae was in its natural position ; and from 

 it a triangular slice was removed for microscopic and other examination. The deeper 

 layers of mucous tissue which are exposed over the site of the placenta, artificially 

 removed in the hope of saving the animal's life, are richly injected ; the undisturbed 

 superficial layer, the homologue of the human decidua vera, is of a uniform opaque white, 

 the injection nowhere showing its colour through its smooth unbroken surface. This 

 layer of mucous membrane abuts upon the remaining placenta a little way within its 

 outer rim, and upon its uterine surface; whereas in the human subject it becomes con- 

 tinuous with it at its free edge, or even joins it a little within this on the foetal aspect. 

 In fig. 9 a representation of a vertical section of a part of the placenta, with portions of 

 chorion and of other deciduous and non-deciduous membranes in connexion with it, is 

 given. In the section of the placenta we see the arborescent upgrowths which carry 

 the vilh, and the downward processes of maternal tissue^, more plainly than we see their 

 homologues, at least with the naked eye, in the lower Mammals of which we have been 

 speaking. The uterine surface of the placenta is clothed by a smooth continuous 

 membrane, from which these " Decidua- Fortsatze " pass downwards into it. Above the 

 placenta a thin but coherent lamina of membrane (o s) is seen, left partly in apposition 

 with, partly divaricated from it, and joining the decidua vera at the point where it 

 impinges upon the after-birth. In its distinctness, and ready separability, and cohe- 

 rence, it resembles the deciduous serotina of the Rodents ; but there can be little doubt 

 that it does not make up the whole of that layer in the Macaque, but that more or less 

 of the tissue between it and the deeper strata clothing the muscular walls, viz. the 

 persistent non-deciduous serotina, would in the natural order of events have been 

 deciduous likewise. More than the thin lamina (d s) may be seen to have been deci- 

 duous in the natural labour of a Macacus rhesus, of which the after-birth is preserved . 



• Kolliker, I. e. p. 164. 



^ These are the " Decidua-Fortsatze " of Eeker (Icones Physiologies, taf. 28. fig. 1, df). They are described 

 by Kolliker (Entwickelungsgeschichte, p. 145), and well figured by Dr. Priestley (Lectures, p. 57. fig. 16), iu the 

 Human placenta at sLx months, after Van der Kolk. They are much less prominent in the Human placenta at 

 full time. Cf. KblUker, I. c. pp. 143, 177, 183. 



VOL. V. — PART IV. 2 B • 



