80 ON THE PLACENTAL STRUCTURES OF THE TENREC 



and the adoption of it would consequently cause confusion. That 

 the utero-placental area is, after parturition, covered by a layer of 

 mucous tissue, and that the muscular coat is not laid bare at that 

 period, but protected by a more or less consistent and coherent 

 coating, to which I would affix the name of ' non-deciduous sero- 

 tina/ was clearly shown, in the year 1853, by Dr. Matthews 

 Duncan \ and has been subsequently confirmed by Drs. Chisholm 

 and Priestley 2 in Great Britain and by M. Robin in France. 



This is not the place for histological and pathological details, 

 such as will be found in the literature to which I have just re- 

 ferred ; but, from a zoological point of view, it may be remarked 

 that the fact of the non-regeneration of the uterine cotyledons of the 

 ruminant, after accidental separation of them from the uterine wall, 

 lends the strongest confirmation to Dr. Matthews Duncan's views. 

 It has been most satisfactorily shown 3 that, after such an occur- 

 rence, the place of the lost cotyledon is occupied not by fresh 

 mucous membrane, but merely by a white cicatrix. 



I will now proceed to contrast and compare the foetal and 

 maternal structures in connexion with the placenta of certain other 

 mammals with their homologues already described in the tenrec. 



Insectivora and Cliirojotera. 



In the hedgehog (Erinaceus europaeus), at a time when the foetus 

 is about one-third the size of that of the foetal tenrec here de- 

 scribed, and the yelk-sac is as large as the amniotic, the non-de- 

 ciduous serotina is separable as a perfectly distinct and coherent 

 coat from the circular muscular coat which it overlies ; the de- 

 ciduous serotina is a very thick mass, bell-shaped, with its convex 

 end attached to the non-placental mucous membrane by a thin 

 peripheral parapet, within which vessels and cellular tissue connect 

 it with the utero-placental area. Exteriorly to the attachment of 

 the delicate parapet of non-placental mucous membrane, the ex- 

 ternal surface of the deciduous serotina becomes smooth, and it 

 may here take the name of ' decidua reflexa,' whilst its internal 

 surface, in apposition with the ovum, remains rough and flocculent. 



1 'Edinburgh Monthly Med. Journ.,' Sept. 1853. See also ' Medico-Chirurgical 

 Eeview,' Oct. 1853; 'Edinburgh Monthly Med. Journ.,' Dec. 1857, Feb. 1858; 

 Obstetrical Society's Trans., vol. iv, April 1859, April 1862. 



2 ' Edinburgh Monthly Med. Journal,' Sept. 1854 ; ibid. Jan. 1857. 



3 M. Goubaux, cit. Colin, 'Physiologic Comparee,' vol. ii. p. 612. 



