PLACENTAL STRUCTURES OF THE TENREC. 291 



Of the foetus (now unfortunately lost) of a Vampire {Phyllostoma hastatum) I have 

 the following note: — "The ovum was five eighths of an inch long. There was a con- 

 siderable, if not complete, decidua reflexa. Next to the decidua refiexa came the 

 chorion, to which, as in the RodentS; an omphalo-mesenteric artery went." In the 

 uterus of this Bat (which I still possess) the non-deciduous serotina is, as in the 

 Insectivora, separable from the circular, and this again from the muscular coat. 



Neither in the Shrew nor in the Vampire have I any note of the umbilical vesicle. In 

 the foetus of the Mole, however, and Pteropus I have observed it to be present, and large. 



Before passing on to a comparison of the Tenrec's placental structures with those of 

 other orders of Mammalia, it may be well to enumerate the points in which they differ 

 from those of the, perhaps, most nearly allied order, Chiroptera, as well as from those 

 of other Insectivora. These points of difference, then, are the absence of a yelk-sac, 

 of the allantois as a distinct sac, and of any membrane, either decidual or chorionic, on 

 the exterior of the amnios. The upgrowth of the chorion in the Tenrec, its attachment 

 to the periphery of the utero-placental area, and the division of this area into two 

 regions are points peculiar to this creature. Aberrant thus in its placenta, it is 

 aberrant from those nearest of kin to it in several other peculiarities pointing towards 

 marsupial affinities. Of these it may sufiice to mention the involution of its lower-jaw 

 angle, and the reception of its lower canine into a fossa in the upper jaw. 



Carnivora. 



A Bull-bitch {Cunis familiaris) which had been impregnated, it was believed, by a 

 dog of much larger size, was delivered, with artificial help, of one of two foetuses at full 

 time. The other foetus was retained in the left uterine cornu, the life of the mother, 

 (the vagina having been ruptured) having come to an end after the birth of the first. 

 The uterus and vagina were brought to me, together with their contents, by Dr. Tuck- 

 well, and I am thus enabled to give the following account of the state of the after- 

 birth, and of the uterine walls of the Bitch after parturition. In the right coruu, 

 whence the foetus, which had been expelled, came, the mucous membrane was much 

 corrugated transversely to the long axis of the tube. The zone to which the fcetus had 

 been attached was recognizable by its pale colour, a red injection which had been 

 thrown into the vessels having given a florid tinge to the non-placental mucous coat 

 on either side of it, but having left it of a greyish hue, and by its roughened surface 

 irregular with depending broken ends of vessels and with processes of membrane. It 

 was bounded also on either side by an upstanding parapet, the homologue of the struc- 

 ture u p in the several figures appended. The same description will apply to the 

 mucous coat of the other cornu, with the exception that in it, owing to the retention 

 of the fcetus, no corrugation was observable. On examining the mucous coat of the 

 uterus, it was found to be perfectly continuous over the placental area, to be thicker 

 over that zone and more opake, and to resist disruption at the lines of junction with 



VOL. V. PART IV. 2 Q 



