308 PROFESSOR ROLLESTON ON THE 
a similar extension of the membranes of a foetus lodged in one cornu round into the 
other is not rarely seen, but without any cecal 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 granulation’ 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 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. 
* Barkow, ‘ Zootomische Bemerkungen,’ p. 7, 
? Birnbaum, ‘ Untersuchungen itiber 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. Gefiissverbindung, p. 14. fig. 1. 
