222 NATURAL SCIENCE. Marcr, 
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 Senor 
Ameghino, the author has been well advised ; 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 Allotheria, 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. 












Fic. 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 Allotheria (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 (Myrmecobius) the repre- 
sentative of a distinct family, but there is surely none for placing the 
Peramelide between that family and the Dasyuride. 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 Thylacoleo 
and the Phalangers from the Kangaroos (Macropodide). 
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 
