PLACENTAL STRUCTURES OF THE TENREC. 289 



" serotina," or to the now exploded theory which the word was intended to bring 

 before the mind) to call " deciduous serotina " ; the utero-placental mucous area (fig. 2) 

 I would call "non-deciduous serotina" ; and the spongy structure (fig. 1) made up of 

 villi and umbilical vessels, and, in all placental mammals (except Cetacea, Artiodactyles, 

 and Perissodactyles, and possibly Bruta), of more or less maternal structure inextricably 

 intermixed as well, I would call "placenta." The word "after-birth" includes 

 " placenta " and " deciduous serotina," both usually, though not invariably, coming 

 away together. 



Owing to errors of observation, the name " decidua serotina" has been applied to 

 the structure I would call " non-deciduous serotina," as well as to that to which Dr. 

 Priestley', like myself, would limit it. It is called " parietal decidua" by Professor 

 Goodsir", and " caduque intero-placentaire " by M. Robin^. And in an account of 

 it given by Professor Kolliker, I find him speaking of it in the Human subject as 

 " eine zusammenhangende Haut wenn er gut erhalten ist"*. It is sometimes called 

 "placenta materna " ; but this phrase is applied to the maternal element of the 

 " placenta" also, 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 serotina," was 

 clearly shown, in the year 1853, by Dr. Matthews Duncan% and has been subsequently 

 confirmed by Drs. Chisholm and Priestley" 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 referred ; 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 wail, lends the strongest 

 confirmation to Dr. Matthews Duncan's views. It has been most satisfactorily shown'' 

 that, after such an occurrence, 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. 



' On the Development of the Gravid Uterus, pp. 2'2 & 48, 1860. 



' Anatomical and Pathological Observations, 184.5, p. 60, pi. 3. fig. 6. 



' M^m. Acad. Imp. Med. Paris, 1861, torn. xxvi. pp. 131 & 141, where there is a disquisition on its histology. 

 See also Cazeau, 'Traite des Accouchements,' 1856, pp. 192 & 202. ' /. c. pp. 145 & 158. 



' Edinburgh Monthly Med. Journ. Sept. 1853. See also Medico-Chirurgical Review, Oct. 1853; Edinburgh 

 Month. Med. Journ., Dec. 1857, Feb. 1858; Obstetrical Society's Trans, vol. iv. April 1859, May 1862. 



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



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



