1898] SOME NEW BOOKS — 423 
Two features of the book are prominent. One, for which the 
author expresses indebtedness to the late Prof. Green, is a constant 
appeal to actual observation and experiment, the value of which in so 
practical a science as geology can hardly be overrated. The other, 
which is indeed the natural corollary of the former, is the introduction 
of numerous photographs of actual sections and views of geological 
interest. For this Mr Watts has peculiar facilities, as secretary to the 
British Association Committee for collecting and preserving such 
photographs. On the whole these photographs are well selected, and 
add greatly to the attractiveness of the book. But nearly all of them 
suffer from the printing, and there are many which we have found in 
actual use to be unintelligible to the student. Figures 13 and 19, 
purporting to show Crinoidal and Wenlock Limestone, might be 
almost anything, so great is the reduction. Figures 18, 60, 88, 104, 
154, 155, 296, 297, 301, are among those that would have been more 
effective as pen-and-ink line-drawings, such as the excellent fig. 53. 
The introduction of cross-country sections is to be commended; but 
the compression of a section across the Snowdon range or the ancient 
rocks of Pembrokeshire into three inches does not make its unravel- 
ment either easy or pleasurable. We rejoice to see that the very clear 
woodcuts of De la Beche are still available. As for the figures 
borrowed from Zittel and distinguished by (Z), Mr Watts doubtless 
knows who the true authors of most of them were and has suppressed 
the intelligence after due consideration. We allude to this because 
there is a lamentable tendency on the part of text-book writers to 
copy figures from other text-books, and to give credit to the copyist or 
compiler rather than to the original author. Thus the student is led 
in a mazy round and not to the fountain-head. 
In style and arrangement the work is remarkably clear. General 
or doubtful statements receive their necessary qualification, so often 
omitted in elementary text-books. Errors there may be, but they 
are not very serious. One fault should be remedied in a future 
edition ; that is the introduction of technical terms in the legends to 
figures, without any explanation in the text, or without cross-reference 
to such explanation if given on a later page. Ice-tables, for instance, 
should either have been explained, or they should not have had a 
half-page illustration devoted to them. 
The book is a fitting celebration of Mr Watts’ appointment to 
an assistant-professorship at Mason College, Birmingham. On its 
appearance, both the author and the beginner in geology are to be 
congratulated. 
THE AFFINITIES OF ANIMALS 
L’ANATOMIE COMPAREE DES ANIMAUX BaskE suR L’EMBRYOLOGIE. Par Louis Roule. 
8vo, pp. xxvi+1972, with 1202 figures. Paris: Masson et Cie. 1898. Price 
48 francs. 
Mr Rovte is Professor at the University of Toulouse and is well 
known by his works “Embryologie générale” and ‘“ Embryologie 
comparée,” to which the two bulky tomes before us form a natural 
sequel. The object of the book is not to give either a systematic 
summary of the whole animal kingdom, a detailed account of its 
numerous variations of structure, or even an elaborate discussion of 
