November 1898] SOME NEW BOOKS 341 



Acrania (represented by the lancelets) and the Oraniota (all other 

 known vertebrates). Of the latter there are three snper-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 

 lchthyes 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 

 Kept ilia 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 

 Reptilian orders appears to us very unnatural, the closely-related 

 < irocodilia and Dinosauria being separated by the Chelonia, while the 

 latter again are divorced from the Theromorpha and Plesiosauria, their 

 undoubtedly nearest allies. Eecent 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. VV. 



