82 REVIEWS 
The Grundziige der Paldontologie, which forms the basis of the pres- 
ent work, is an essentially modern, useful, and very compact treatise. It 
compasses within 900 odd pages the whole field of paleozoGlogy, rather 
more than one half of the space being devoted to invertebrates. The 
descriptions of genera are brief but to the point, the illustrations 
numerous, and the arrangement simple and well-balanced. These are 
salutary features for any elementary text-book to possess, and the writ- 
ings of von Zittel have set a high standard for other authors to emu- 
late. 
As compared with the original, we note in the first place that the 
English edition devotes about 200 more pages to the invertebrates, 
and is enriched by nearly 100 new figures. Over 4600 generic names 
are enumerated in the index, being about 1200 in excess of the inver- 
tebrates treated in the German edition. The amount of enlargement 
is therefore considerable, and the new genera introduced are mostly 
those which are of importance in American and British strata. 
All the generic diagnoses are of necessity very brief, and large 
numbers of names are cited without definition, simply as an index to 
their family position, or degree of family differentiation. Typical or 
otherwise interesting forms are treated more at length, and in some 
instances type-species are listed ; but the definitions of families and 
larger groups are as a rule succinctly yet carefully stated. The book 
serves as an excellent guide for orientation over the different groups 
and as a catalogue of the more important genera, but does not permit 
of the identification of less important genera without the aid of special 
literature. In compensation for this, copious bibliographies are 
inserted under nearly every caption, those for the Cephalopods and 
Trilobites being especially complete and all of them brought strictly 
up to date. 
Many radical changes are to be observed in the classification, the 
responsibility for which, we are told in the preface, lies with the 
revisers of the different sections. The rearrangement of Pelecypod 
families and genera by Dr. W. H. Dall is in accordance with the latest con- 
ceptions of this eminent conchological authority. Great emphasis is laid 
by Dr. Dall on the distinctness of family groups, and many well-known 
genera are taken by him to represent types of new families, or sub- 
families. Noris Dr. Dall alone in this tendency toward elevation of 
families out of generic characters ; it seems to be becoming more and 
more the fashion in all branches of systematic biology, and probably 
