AND THOSE OF CEETAIN OTHEE MAMMALIA. 83 



was recognisable 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 depend- 

 ing broken ends of vessels and with processes of membrane. It 

 was bounded also on either side by an upstanding parapet. 



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 

 foetus, 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 opaque, 

 and to resist disruption at the lines of junction with the non- 

 placental portions of the coat with the greatest tenacity; and, as 

 in the hedgehog and in the vampire (Phyllostoma hastata), the 

 mucous coat of the placental area, or persistent serotina, was 

 readily detachable, as a distinct and coherent layer, from the 

 circular muscular coat, and this again from the longitudinal. Ex- 

 amined with the microscope, the utero-placental zone was found to 

 contain abundance of tubular glands, as was also the homologous 

 layer in the uterus of a cat at full time. The membranes of the 

 undischarged foetus had been ruptured, and the placental zone 

 broken across. The uterine surface was rough and shreddy; but 

 no distinct deciduous serotina could be raised from its surface (as 

 there can be from that of the cat at full time in a continuous ring- 

 like sheet). Of the absence of the decidua serotina in the foetal 

 membranes of the dog at full time both Bojanus 1 and Von Baer 2 

 were aware, though neither of them states that it is present at the 

 same time in the cat. If we look, however, at the uterine surface of 

 the placenta of the dog at full time, we shall see upon it shreds of 

 membrane which, on floating the structure out under water, are 

 observed to form a more or less regular polygonal reticulation. 

 This network of upstanding laminae is the remnant of what was a 

 separable membrane at earlier periods. This will appear the more 

 clearly from a description of the placenta, deciduous, and non- 

 deciduous serotina of the foetal dog at about a month of intra- 

 uterine life. 



The non-deciduous serotina is then distinctly visible as a villous 



1 'Nova Acta,' torn. x. p. 143, 1820. 



2 'Entwickelungsgeschichte,' ii. p. 242, 1837. 



G 2 



