PLACENTAL STRUCTURES OF THE TENREC. 293 



and the greater relative abundance of all the other elements, and the smaller conse- 

 quent size of the honeycomb vacuoles, may account for the maintenance by it of an 

 independent existence up to the period of parturition. It exists, however, in the Cat 

 at full time rather as a separable than as a coherent layer. In the Dog it is neither 

 coherent nor separable from the placenta'. 



It is difficult to see how, with the honeycomb-like decidua serotina of the foetal Dog 

 placed in relation with the mucous membrane of the unimpregnated and unenlarged 

 uterus of the bitch as figured by Dr. Sharpey^ before one, it is possible to cast the doubt 

 upon that observer's views which M. Robin has done^ It is obvious that when glands 

 or follicles are arranged as closely together as in the figure referred to, all increase of 

 their calibre must take place by means of outgrowth of interfollicular or interglandular 

 substance, and that, admitting the facts which are incontrovertible, the contradiction of 

 of M. Robin amounts but to a dispute* as to the use of words. Bischoflfs assertion'^, 

 that the cotyledons of the Roe (Cervus capreolus) are devoid of utricular glands, amounts 

 to more than a verbal question; but as Eschricht and Von Baer had noted their 

 absence in the similar structures of ordinary Ruminants^ many years previously, this 

 observation has little claim to be quoted as novel. 



The decidua reflexa can be scarcely said to be present even as a mere rudiment in 

 Carnivora. The mucous secretion found exteriorly to the chorion may perhaps be con- 

 sidered as homologous with the distal part of what in other orders is a coherent, more 

 or less perfectly encapsulating membrane. 



I have not observed, nor do I know, that any observations have been made showing 

 that any variations exist as to the relations or degree of development of the allantois, 

 amnios, or umbilical vesicle within the class Carnivora. 



Von Baer's words {I. c. p. 243), " Vielleicht weicht das Ei der Sohlenganger, das ich 

 nicht kenne in einiger Hinsicht, ab ; beim litis ist der Giirtel des Fruchtkuchens nicht 

 vollstandig," refer in all probability to the description given of the placenta of the 

 Ferret by Daubenton, in the ' Histoire Naturelle,' torn. vii. 1 758. " litis " is ordinarily 

 used to denote the Polecat [Mustela putorius) ; but Von Baer may have thought himself 

 justified in considering the Polecat and Ferret as of the same species, and using the 

 term " litis " as an equivalent for Mustela furo. Breschet^ however, is in no way justi- 



' It would seem from Barkow's description of the fcEtal membranes of a Seal {Phoea vitulina), that the 

 decidua serotina possesses both these characters in that animal (Zootomische Bemerkungen, 1851, p. 7). 



- Miiller's 'Physiology,' translated by Dr. Baly, p. 1575. 



■' Robin, /. c. p. 132, " Les villosites des cotyledons ou du chorion de I'homme et des autres mammiferes tels 

 que ruminants, rongeurs, carnassiers, soUpedes, et fissipedes, n'enfoncent pas, comme on le dit, leurs subdivisions 

 terminales dans les glandes tubuleuses de la muqueuse uterine." 



' See also Goodsir, ' Anat. and Path. Observations,' 1845, p. 58 ; and Henle, ' Handbuch der Eingeweidelehre,' 

 1862, p. 402. 



= ' Entwickelungsgeschichte des Rehes,' 1854, p. 22, fig. 43, cit. Kolliker, /. c. p. 170. 



* Von Baer, ' Gefiissverbindung,' p. 16. Eschricht, 'De Organis,' p. 36. 



' 'Memoires de I'Institut,' torn. six. p. 457. 



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