82 ON THE PLACENTAL STRUCTURES OF THE TENREC 



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 considerable, if not complete, de- 

 cidua reflexa. Next to the decidua reflexa 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 Pterojous 

 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 

 orders, 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 suffice 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 (Canis 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. Tuckwell, 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 cornu, 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 foetus had been attached 



