306 PROFESSOR ROLLESTON ON THE 



sponds, if we exclude the Edentata provisionally, and include, with perhaps more con- 

 fidence, the Sirenia, exactly with the Ungulata and Mutica of Linnaeus, and with the 

 Artiodactyla, Perissodactyla, and Mutilata of Professor Owen's classification in the 

 Linnean Society's ' Proceedings.' Of all these animals alike it may be predicated that 

 at parturition the villi of the chorion separate themselves from the maternal structures, 

 in which previously they were ensheathed, without bringing away any of these struc- 

 tures, either interfused with, or superposed upon them ; and for the entire class the term 

 " non-deciduate " is proposed by Professor Huxley. The first question which arises is, 

 What number of general propositions can we make as to the entirety of this class, to 

 a certain similarity existing between the least mutually resembling members of which, 

 testimony is borne by the trivial names of " Sea-Cow " and " Sea-Camel " as applied to 

 certain of the herbivorous, and " Meerschwein " to certain of the carnivorous Cetacea? 

 There is a considerable number of such propositions ; but it is not always easy to say 

 whether certain of them are not correlated, either in the way of nutrition with the large 

 size which distinguishes this division of placentals as a whole, or in the way of function 

 with their peculiar modes of life, and are therefore of little classificatory value. It is as 

 functional correlations, perhaps, that we should note the absence of clavicles and the 

 faculty of self-help which the young of all non-deciduate Mammals possess from their 

 first entrance into the world ; and I should incline to consider as a correlation of growth 

 the possession of complexly convoluted brains by these animals, since, in the class to 

 which they and their deciduate allies both belong, the complexity of the convolutions 

 varies very commonly in a direct ratio with the increase of bulk. Neither of these 

 explanations, however, will account for the fact that in all the non-deciduate Mammalia 

 we find one superior cava, and one only, and that in the whole class, so few of the 

 members of which are multiparous, the uterus still retains a bifid character, its cornua 

 greatly predominating over the corpus uteri. In antithesis to the deciduate Mammals, 

 we find in the non-deciduate a general, though not a universal, coexistence of com- 

 paratively simple livers and simple lungs with complex stomachs. I am not aware that 

 anal glands have been observed in any non-deciduate Mammal. It is well known that 

 the generative organs of both sexes in the Artiodactyles and the Cetacea proper are 

 "almost exactly similar', only that the testicles are not external and there are no 

 external parts in the females " of the latter order. 



The great abundance of blood and the great relative abundance of blood-cells are 

 points common to the Pig and to the Porpoise ; and it may be remarked that the halitus 

 evolved on opening the great cavities of each of these animals possesses a very similar 

 odour. Upon the first of these two points, perhaps, little stress should be laid, as it 

 may be either a result or a necessity of the mode of life of either creature ; and the 

 latter, depending entirely upon the evidence of the sense of smell, has consequently 

 but a subjective cogency. Much greater importance should be assigned to the state- 



' Hunter's 'Essays and Observations,' ed. Owen, vol. ii. p. 105 ; and Hunterian Catalogue, vol. iv. 2527. 



