November 1898] SOME NEW BOOKS 341 
Acrania (represented by the lancelets) and the Craniota (all other 
known vertebrates). Of the latter there are three super-classes, 
Cyclostomata, Hypostomata, and Gnathostomata. The Cyclostomata 
are arranged in the usual manner. The Hypostomata (new term) are 
the extinct Ostracodermi of Cope. The Gnathostomata comprise the 
classes Ichthyes, Amphibia, Reptilia, Aves, and Mammalia. The 
Ichthyes are again subdivided into the sub-classes of Pisces and 
Dipnoi, and our present knowledge of extinct fishes is specially taken 
into account in arranging the minor groups, among which ‘ Ganoidei’ 
survives no longer, except in a footnote. The arrangement of the 
Amphibia depends chiefly upon Cope, Boulenger, and Zittel. The 
Reptilia are grouped in eleven sub-classes, of which seven are extinct. 
The classification of the Aves is based very largely.on the author’s 
own researches, while that of the Mammalia corresponds closely with 
that of Flower and Huxley. 
The authorship of the names of the larger divisions is usually 
mentioned, and the student is helped occasionally by the addition of 
synonymous terms. The author’s researches, however, into the 
literature of the subject do not appear to have always extended to the 
original sources, and hence several errors which ought to be corrected 
in a future edition, Among other terms for which a wrong author- 
ship is given, we may enumerate Antiarcha, Teleostomi, Pareiosauri, 
Dinosauria, and Mesosauri. The equivalent terms, also, are not 
invariably exact; for instance, the Marsupialia are not precisely the 
Metatheria of Huxley, but merely the specialised surviving repre- 
sentatives of that sub-class. Moreover, we disapprove of the use of 
one and the same ordinal term (Lepospondyli) in two distinct classes, 
and the corresponding wide separation of two such closely related 
genera as Keraterpeton and Hyloplesion. The arrangement of the 
teptilian orders appears to us very unnatural, the closely-related 
Crocodilia and Dinosauria being separated by the Chelonia, while the 
latter again are divorced from the Theromorpha and Plesiosauria, their 
undoubtedly nearest allies. Recent discoveries in Palaeontology seem 
to have rendered the Chelonian orders Thecophora and Athecae un- 
tenable. We also object to one theory of the quadrate bone being 
stated dogmatically as a fact in the definition of the Mammalia. For 
actual errors in the diagnosis, however, we have looked almost 
in vain. There is nothing more seriously incorrect than the state- 
ment that all Cetacean teeth are destitute of enamel, or that Squalodon 
has only one-rooted teeth. The index of proper names, too, is 
admirably done, most terms having their derivation appended. 
At the end of his work Dr Gadow adds a useful chapter on the 
geographical distribution of the Vertebrata, with a table showing the 
approximate number of the known recent species. He also gives 
a fanciful though striking calculation to show how some groups 
are still in the ascendant while others are distinctly declining. The 
little volume is, indeed, a welcome addition to the biological student’s 
library, and it deserves the wide circulation which its author's 
eminence is likely to ensure for it. A. S. W. 
