in the Reconstruction of extinct Vertebrate Forms. 483 



nassial than the Ursus sju'lmis, or any of its existing eongeners " 

 (Owen, Odontography, vol. i. p. 501). The same conclusion 

 had been previously arrived at by the original dcscribers of this 

 species, from the combined indications of the skull and teeth*. 

 Here then are two fossil bears, the one of which is inferred to 

 have been more of a vegetable feeder, and the other more car- 

 nivorous, from characters of correlation presented by their skulls 

 and teeth ; — being practical refutations of the assertion made by 

 Mr. Huxley. It is true that the legitimacy of the deductions 

 may be questioned or denied : all that can be said in reply is, 

 that if the propositions, positive and negative, are considered 

 according to the degree of their respective probability, the verdict 

 of every competent judge will be in favour of the former. Of 

 more than this, a case of the kind does not admit. 



Mr. Huxley next takes in hand the opposite case of the Un- 

 gulate Herbivora, as put by Cuvier. They present the simplest 

 and most unmixed types of the strictly vegetable feeders, and 

 their organization is modified throughout, in a scries of adapta- 

 tions in contrast with those presented by the Digitiyrade Carni- 

 vora, and in necessary correlation with each other (i. e. necessary 

 in the sense of being demonstrable in such a way that the con- 

 trary involves an absurdity and is inconceivable). \\'e will take 

 Mr. Huxley^s objections in the order suggested by the analysis. 

 Cuvier states that : " Their herbivorous habit wall require teeth 

 with flat crowns to bruise up the grain and herbage; this crown 

 must needs be unequal, and to this end enamel must alternate 

 with the bony materials." Mr. Huxley attempts to refute the 

 generality of the proposition by the case of the Sloth. He says, 

 " The Sloth is purely herbivorous, but its teeth present no trace 

 of any such alternation of substauce.^^ It will be shown in the 

 sequel, that they do present such alternation ; but the first re- 

 mark that is suggested is, that in an argument where there is 

 an ex})ress specification of the premises, it is inadmissible to 

 adduce a case that does not come within the terms. Cuvier 

 specifies the Ungulata (including the Pachydermata, Solidungula, 

 and Ruminantia) : Mr. Huxley meets him with the Sloth, which, 

 although herbivorous, does not belong to either, but to the order 

 Bruta, comprising animals very different in their habits and 

 organization from the Ungulata. The mass of the species in 

 the one order is constructed for extreme speed, to escape from 

 their predaceous enemies ; while the progression of the mass in 

 the other is extremely slow, but strictly in unison with their 

 habits and wants. Instead of presenting a narrow scapula, with 

 no acromion and no clavicle (conditions expressly specified by 



* Asiatic Researches, vol. xix. p. 200. 



31* 



