PLACENTAL STRUCTURES OF THE TENREC. 287 



sessile', but is connected with it by a short coi'd which meets it at right angles. The 

 peritoneal capsule of the ovary is large and loose, opening by a small orifice into the 

 general cavity of the peritoneum. The ovary itself has, from the small quantity of its 

 stroma, the granulated appearance so well marked in the Shrew and Hedgehog. 



2. Maternal and Foetal Structures developed in utero in connexion with the Embryos. 



Owing to the state of preservation in which the specimen was when it came into my 

 hands, the maternal and foetal structures in connexion with the chorion had, in every 

 case but one, become self-analyzed into three parts. These parts were, first, an area 

 of tissue continuous at its periphery with the non-placental uterine mucous membrane ; 

 (PI. L. fig. 3) ; secondly, a lamina of membrane floating loosely, and, like the utero- 

 placental area, perforated centrally by vascular orifices (fig. 2) ; and, thirdly, the placenta 

 proper (fig. 1), of a diameter of about half an inch. One ovum only retains its natural 

 connexion with the uterine wall ; but in several cases the lamina of membrane (fig. 2) 

 ordinarily found floating loosely remains attached to its utero- placental area. Of this 

 area I will first speak. It is subcircular, and bounded by a slightly raised parapet of 

 uterine mucous membrane (u p, fig. 3), with which an upgrowth of the chorion (ch' 

 fig. 1) was continuous in all the ova, and remains so in one instance at present. The 

 diameter of each utero-placental space thus bounded being about half an inch, its area 

 is divisible into two regions — one, the outer one, being quoit-shaped and surrounding a 

 circular central inner region (p s, fig. 3). The depth of the outer ring is about half the 

 length of the diameter of the entire area ; it is clothed with a mucous membrane of 

 pulpy appearance and corrugated more or less regularly. In being thicker, and in being 

 corrugated, this portion of the utero-placental area contrasts with the mucous coating 

 of non-placental portions of the uterus, the mechanical pressure and contact of the 

 many foetuses accounting, probably, for the smoother and thinner character of the 

 mucous layer in the latter portions of the organ. The central circular portion of each 

 utero-placental area is distinguished, by its irregularly perforated and discoloured ap- 

 pearance, both from the ring-shaped area immediately surrounding it and from the 

 rest of the uterine mucous coat. The membrane covering both regions in each utero- 

 placental area is single, and does not admit of being split up into laminse ; but in several 

 cases, the lamina (fig. 2), more commonly found floating freely, is left adhering to the 

 utero-placental area. This lamina, when free, presents many orifices of blood-vessels, 

 centrally ; and its general structure is loose and pulpy. When adherent to the utero- 

 placental area, it is by its outer margin that it is attached along the line of demarcation 

 between the outer and inner regions of each utero-placental area. In other words, the 

 utero-placental mucous membrane seems to split at this line into two laminse, between 



' The ovary of the Sow is somewhat similavly pedunculate (see ' Ilunterian Catalogue," iv. 2782), audsoalso 

 is that of other animals, as the Rat. 



