33^ 



NATURE 



[August ii, 1898 



poda '■' is based on a misconception, and that there are 

 even some who doubt whether the Hmb-bones assigned 

 to it in this volume are rightly associated. Whenever 

 such doubts exist, either in regard to systematic position 

 or the association of remains, the mention of them is, in 

 our opinion, of prime importance. 



Another point to which we take exception is the 

 author's hesitation in adopting the rule of priority in 

 nomenclature, unless strong reasons exist against it in 

 particular cases. The result of this hesitation is that in 

 many cases we have two names given for a genus as if 

 they were of equal value. We find, for instance, Belodon 

 or Phytosaurus, Hyopotamus or Ancodus, and Giraffa 

 or Camelopardalis. In the third case the introduction of 

 the alternative is obviously superfluous, as it is used by 

 no zoologist with any respect for himself; but in the 

 others, the second name is the one that should be em- 

 ployed. Whether he accept priority or no, the author 

 ought to have made up his mind which name he in- 

 tended to use, and have stuck to that and that alone. 

 The man who hesitates in this respect is lost. 



In regard to the classification of the higher vertebrates, 

 the author follows to a great extent the schemes of some 

 of those by whom he has been preceded. But in certain 

 cases innovations are made, some of them doubtfully 

 advantageous. We fail, for instance, to see the advis- 

 ability of definitely including the problematical Eocene 

 group Tillodontia within the Rodent order, of which it 

 completely destroys the definition. Till their affinities 

 be proved absolutely certain, it seems to us preferable to 

 follow Sir William Flower in regarding such groups as 

 occupying undetermined positions. 



In view of recent discoveries with regard to vestiges of 

 a placenta in certain living marsupials, the author's 

 observations in regard to the phylogeny of that group 

 will be read with special interest. Mr. Woodward is of 

 opinion that marsupials have become non-placental by 

 degeneration, and that the loss of nearly all replacement 

 in the dental series is likewise an acquired feature. But 

 he believes that the little Triconodon of the Dorsetshire 

 Purbeck had already acquired the modern dental type ; 

 and it is consequently to be inferred that marsupials had 

 become differentiated from a primitive placental type by 

 the middle of the Jurassic epoch, and that such mar- 

 supials existed in the northern hemisphere. Now in a 

 later passage (p. 431) we read that "the skeleton of 

 these Australian marsupials does not appear to differ in 

 any essential respects from that of the Creodonta and 

 Condylarthra met with in the northern hemisphere 

 at the dawn of the Eocene period. It is quite likely, 

 therefore, that they [the Australian marsupials] are the 

 direct descendants of some unknown families of the latter 

 groups in the southern hemisphere." But he has already 

 admitted the existence of true marsupials in the northern 

 hemisphere during the Jurassic, and it is, therefore, 

 obvious that, allowing time for migration of the evolved 

 marsupials into the northern hemisphere, " some un- 

 known families of Creodonta and Condylarthra" must 

 have existed in the southern hemisphere at least as early 

 as the Lower Jurassic, if not the Triassic ! If we read the 

 author's meaning correctly, there is no getting away from 

 this crux^ and it is certainly a " large order " that the 

 groups in question should be of such vast antiquity. We 

 NO. 1502, VOL. 58] 



are prepared to accept the origin of the Monotremes 

 from the Anomodonts or some allied Batrachians, and 

 have indeed urged it ourselves ; but, ,in the absence of 

 tangible evidence, to be asked to believe that the 

 Creodonts originated in the Trias or Lower Jura from 

 the Theriodonts (which is practically what the above 

 amounts to) at present staggers our powers of credulity. 



On p. 430 the author revives the old theory as to 

 the complete isolation of Australia " from all other 

 existing continental areas since the remote epoch when 

 Prototheria and Metatheria were the dominant mammals." 

 And in order to support this contention he is compelled 

 to remove the Patagonian Tertiary Prothylacinus (p. 

 388) from the Marsupials, and to place it among the 

 Creodonts. But if an animal with a thylacine-like den- 

 tition (perhaps with somewhat fuller replacement) and 

 skull, and an inflected lower jaw is not a Marsupial, it 

 seems to us that we may as well give up our present 

 system of classification altogether. Moreover, the isola- 

 tion theory involves great difficulties with regard to the 

 origin of the American opossums and selvas and the 

 Australian dasyurids. 



There are, however, difficulties into which the author's 

 fondness for the isolation of continental areas leads him 

 in other parts of the world. On p. 419 we are told that 

 " South America must have been quite an isolated region 

 from the close of the Cretaceous to the dawn of the 

 Pliocene." It is true that on p. 429 this isolation is 

 limited, so far as words go, to North America ; but the 

 general idea conveyed is the same, and nothing is 

 mentioned with regard to the necessity of connection 

 with other lands to explain the evolution of the fauna. 

 The separation from North America is undoubtedly 

 true, and thus far we are glad to be in agreement with 

 the author. But when he speaks of universal isolation 

 since the Cretaceous, it practically implies that the 

 Ungulates and Rodents of South America have had no 

 connection whatever with those of the rest of the world, 

 since it is more than doubtful if these orders, as such, were 

 evolved in Cretaceous times. And we should like to be 

 informed how the occurrence of Octodonts in both South 

 America and Africa is to be explained ; to say nothing 

 of the apparent connection indicated by recent dis- 

 coveries between the African hyraces and the Patagonian 

 Toxodonts and Typotheres. Moreover, in this con- 

 nection the author seems deliberately to have walked 

 into a pitfall of his own digging. The aforesaid Pata- 

 gonian Homalodontotherium is referred (p. 307), in 

 opposition to the views of most writers, to a group of 

 Ungulates known as the Ancylopoda, and typified by the 

 European, Asiatic, and North American genus Chalico- 

 therium. Now Chalicotherium is unknown before the 

 Oligocene, and if South America has been shut off from 

 the rest of the world between the Cretaceous and the 

 Pliocene it would involve the supposition that it origin- 

 ated quite independently of Homalodontotheriuvt ; or, in 

 other words, two members of one and the same group 

 were developed in isolated areas without the possibility 

 of the existence of a common ancestor. 



But this is not all the fault we have to find with Mr. 

 Woodward's treatment of the Ancylopoda. He mentions 

 and describes Homalodontotherium first, so that the 

 unsophisticated student would take that genus (instead 



