January 1, 1897.] 



SCIENCE. 



31 



tion allowed of the immigration from the north 

 of the true Carnivora., such as the existing cats 

 (Felis), the extinct sabre-toothed tigers (Machse- 

 rodus), dogs and foxes (Canidse), bears {Ursus 

 and Arctotherium), raccoons (Procyonidie), skunks 

 and their allies {Miistelidse), together with va- 

 rious ungulates belonging to suborders pre- 

 viously unknown in the realm. These latter 

 include the guanaoo and vicuiia (Lama), of 

 which ancestral forms are abundant in the North 

 American Tertiaries, New World deer (Cari- 

 aous), horses (Equidx) of various genera, tapirs 

 (Tapiridse), peccaries (Dicotylidse) and masto- 

 dons. Among the rodents, squirrels, the various 

 genera of Muridse and the hares, likewise at 

 this epoch made their first appearance on the 

 scene. Opossums also at this time effected an 

 entrance into the land which has now become 

 their chief home." (Pp. 119-120.) 



Having arrived at the conclusion that the 

 Pliocene and present mammal faunas of South 

 America came from North America, and that 

 the earlier faunas could not have been derived 

 from the same source, Mr. Lydekker seeks to 

 account for the origin of the latter. This, he 

 freely admits, " is a difficult and perplexing sub- 

 ject which it is scarcely possible to explain fully 

 in the present imperfect state of paleontologi- 

 cal knowledge." Still, he agrees with Scott, 

 Neumyr and others in the belief that the evi- 

 dence points strongly to an early land connec- 

 tion with Africa and also with Australia. In 

 the case of certain Patagonian marsupials he 

 finds it difiicult to come to any conclusion other 

 than that their ancestors " reached the country 

 from Australia, either by way of the Antarctic 

 continent or by a land bridge in a more north- 

 ern part of the Pacific." Continuing, he ob- 

 serves : "If this be correct, and likewise the 

 supposition that the opossums originated from 

 the ancestral stock in southeastern Asia, it 

 will be evident that Didelphys and Csenolestes 

 met in South America after their ancestors had 

 travelled half around the world in opposite 

 hemispheres. ' ' 



Mr. Lydekker is evidently disturbed by his 

 inability to define to his own satisfaction the 

 Mediterranean region — the analogue of our 

 Sonoran. He speaks of it again and again, but 

 not always in the same way. Thus is one place 



(p. 310) he says : " Could a Mediterranean re- 

 gion be satisfactorily defined, the homogeneity 

 of the mammalian Holarctic fauna would be 

 still more apparent ; but this, from the great 

 mingling of northern and southern types which 

 has taken place in the Old Woi'ld, is, I think, 

 impracticable." Again: " The Mediterranean 

 or Tyrrhenian sub-region has strong claims to 

 be regarded as representing a region by itself" 

 (357). I have no doubt that sooner or later 

 some enterprising natviralist will make a de- 

 tailed study of this region, tabulate its distinc- 

 tive genera and define its tortuous boundaries. 



While it is not the purpose of the present re- 

 view to criticise technical points in classifica- 

 tion, one cannot help wondering on what char- 

 acters the statement is based that the sewellels 

 {Aplodontia) are ' closely allied to the squirrels.' 

 On the other hand, it is pleasing to note that the 

 aard-varks and pangolins are separated from 

 the Edentates proper and given independent 

 ordinal rank, under the name Effodientia. The 

 lemurs are retained among the Primates — the 

 usual and conservative course. Prof. Hubrecht 

 has recently shown that the embryology and 

 placentation of the Lemuroidea indicate that 

 these animals are entitled to rank as an inde- 

 pendent order, and that Tarsius is not a Lemu- 

 roid at all, but the earliest known Primate. He 

 finds that the fossil genus Anaptomorphus of 

 Cope is intermediate between Tarsius and the 

 higher Primates, while Tarsius itself looks back 

 to an ancestry suggesting the genus Erinaceus 

 of the heterogeneous order Insectivora. Prof. 

 Wilhelm Leche, from a study of the teeth, ar- 

 rives at somewhat different conclusions. 



The interesting and highly important subject 

 of the geographic ' centers of evolution ' is dis- 

 missed with a single page, where it is handled 

 gingerly and in general terms only. In view of 

 the standpoint from which the book is written 

 — that of the paleontologist — it seems as if a 

 chapter had been omitted — a chapter on the 

 centers of origin, in time and space, of the dif- 

 ferent groups of mammals. Much information 

 of this kind is scattered through the book, but 

 it would be exceedingly convenient to have it 

 epitomized by groups. 



Evidences of haste in the preparation of Mr. 

 Lydekker's book crop out here and there, par- 



