222 



NATURAL SCIENCE. 



March, 



has been involved in an intricate labyrinth of confusion, from which 

 it can only with much labour and care be freed. We are persuaded, 

 however, that in accepting in the main the conclusions of Sehor 

 Ameghino, the author has been well ad\'ised ; and we are glad to see 

 the newly-discovered Argentine Tertiary Marsupials placed next the 

 living Australian Thylacine. 



Almost the only portion of the work that we do not like is the 

 classification which the author has seen fit to adopt. In place of 

 dividing Mammals into the three primary groups of Ornithodelphians 

 (Monotremes), Didelphians (Marsupials), and Placentals, Professor 

 Zittel takes only two primary groups, namely, Eplacentals and 

 Placentals ; the former including the Monotremes and Marsupials, 

 together with the extinct AUotheria, or Multituberculata. Now, we 

 are fully prepared to admit that there is much to be said in favour of 

 a binary instead of a ternary subdivision of the Mammalian class. If, 

 however, such binary scheme of classification be thought advisable, 

 we have no hesitation in saying that the Monotremes (together with 

 the Multituberculata) should form one subclass, while the Marsupials 

 should be brigaded with the Placentals in the second, and that there 

 is no sort of justification for the scheme followed by our author. 



Fig. 2. — Restored skeleton of Glyptodon, with the tail incomplete. 



The present fasciculus includes the Monotremes, Multitubercu- 

 lata, Marsupials, Edentates, Cetaceans, Sirenians, and the Condy- 

 larthrous and Perissodactylate sections of the Ungulates. 



A large space is devoted to the Mesozoic Mammals, among which 

 the AUotheria (Multituberculata) are assigned a rank equivalent to 

 that of the Monotremes, while all the other forms are included (and 

 we believe rightly) among the Marsupials, some of the Cretaceous 

 types being even placed in an existing family. There may be some 

 justification for making the Banded Anteater [Myrmecobiiis) the repre- 

 sentative of a distinct family, but there is surely none for placing the 

 Peramelidae between that family and the Dasyuridas. Then, again, we 

 must take exception to making the Rat-kangaroos a distinct family 

 (to which, by the way, a wrong name is given) separated by Tliylacoleo 

 and the Phalangers from the Kangaroos (Macropodidae). 



In the Edentates, special interest attaches to the excellent 

 restorations of the skeletons of the Glyptodonts, one of which is 

 herewith given. We are, however, persuaded that the division of the 

 Ground-Sloths into several distinct families is not justifiable. We 

 notice that the author has seen no reason to follow certain new views 



