AND THOSE OF CERTAIN OTHER MAMMALIA. 105 



On the other hand, numbers of rough granulations exist between 

 the layers of the chorion, and project into the sac of the allantois of 

 this animal at full time ; and these structures must find their 

 homologues in the similarly placed outgrowths described by Pro- 

 fessor Owen in the membranes of the elephant, and possibly also 

 in the ' hippomanes' of Solipeds 1 . I have observed those growths 

 in the membranes of an embryonic pig of 5 inches in length ; and 

 also in the appendices allantoidis of the ruminants. From an 

 examination of the membranes of an embryonic cetacean of 7 inches 

 in length, I am inclined to say they exist there also. But a fresh 

 or well-preserved specimen is necessary to decide this point 2 . 

 Finally, the cornual ends of the cetacean membranes just alluded 

 to are bare and glabrous as compared with the villous characters 

 of the rest of the chorion. It is possible that this appearance may 

 have been produced by the treatment to which the membranes 

 were subjected before they came into my hands ; but it is also 

 possible that it may be another point of resemblance between the 

 placenta of the cetacean and of the artiodactyla as described and 

 figured by Von Baer 3 . The condition of the cetacean membranes 

 which I have been able to examine has not been such as to enable 

 me to make out the relations of the allantois either to the circum- 

 ference of the amnios within, or to that of the villous membrane 

 exteriorly. It would be highly interesting and important to have 

 as accurate records of the relations of these parts in the Mutica as 

 we have already of those of the same structures in the Ungulates. 

 In the meanwhile it may be anticipated that no such differences 

 will be discovered as the very great ones which distinguish the 

 carnivorous membranes from those of the other three classes of 

 deciduate mammals of which we have been speaking. Professor 

 Kolliker (1. c. p. 169), whilst adopting Weber's class of deciduate 

 Mammalia, has divided his non-deciduate class into two, the first 



1 • Hunterian Catalogue,' vol. v. 3558, A. 



2 Such a specimen would be further valuable, as it would enable one to discover 

 whether the Cetacea possess that peculiar vascular arrangement which Von Baer and 

 Eschricht have described in the membranes of the Artiodactyles, and which we may 

 call a • placental portal circulation/ Eschricht, p. 36 ; Von Baer, * Die Gefassver- 

 bindung,' p. 10. 



3 Entwickelungsgeschichte,' 252, 254, tab. v. fig. 5; ' Gef assverbindung,' p. 14. 

 fig. 1. [The presence of spots on the chorion free from villi both at the poles and at 

 the surface next the os uteri has been described by the Editor both in Orca gladiator 

 and in the Narwhal. ' Trans. Koy. Soc. Edinb.' 1871, and 'Proa' 1876.] 



