308 PROFESSOR ROLLESTON ON THE 



a similar extension of the membranes of a fcEtus lodged in one cornu round into the 

 other is not rarely seen, but without any caecal diverticulum markedly developed in 

 their short corpora uteri. The multiparous Sow does not, of course, resemble its less 

 fertile congeners in this particular; but the membranes of the deciduate and ordinarily 

 uniparous Seal {Phoca vitulina) have been observed to be confined to the uterine cornu 

 which contained its single foetus'. 



Secondly, we find on the umbilical cord of the foetal Cetacean, filiform outgrowths of 

 the amnios which are undoubtedly homologous with the similarly placed growths in the 

 early Ruminant, and in the soliped embryo, as well as with those on the amnios of the 

 Tenrec, as already described. In the amnios of the Pig no such growths are observable, 

 but certain dilated microscopic vesicles^ have been supposed to take their place and 

 function. 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 Professor Owen in the membranes of the Elephant, and possibly also in the " hip- 

 pomanes" of Solipeds^. I have observed these growths in the membranes of an em- 

 bryonic Pig of 5 inches in length ; and also in the appendices allantoidis of the Rumi- 

 nants. 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*. Finally, the cornual ends of the Cetacean 

 membranes just alluded to are bare and glabrous as compared with the villous character 

 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^. 



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 

 circumference 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 difiierences 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. 



' Barkow, ' Zootomische Bemerkungen,' p. 7. 



" Birnbaum, ' Untersuchungeu iiber den Bau der Eihiiute,' Berlin, 1863, pp. 18 & 67. 



" Hunterian Catalogue, vol. v. 3558, A. 



" 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." 



° Entwickelungsgeschichte, 252, 254, tab. v. fig. 5. Gefassverbindung, p. 14. fig. 1. 



