March 23, 191 1] 



NATURE 



107 



as important as that between the Keewatin and the 

 Lower Huronian. Hence he is forced to oppose the 

 division of the pre-Cambrian rocks into Archaean and 

 Algonkian only. The early Palaeozoic faunas fall 

 naturally to the care of Dr. C. D. Walcott, who 

 interestingly describes the oldest known Cambrian 

 beds, those of south-western Nevada and eastern Cali- 

 fornia (p. 31). In Nevadia weeksi, referred at first to 

 Holmia, he recognises a form of trilobite "more 

 primitive than such forms as Olenellus thompsoni 

 (Hall) and Holmia broggeri (Walcott.) " This phrase 

 reminds us of the dangers that lie in wait for the 

 palaeontologist. Seeing that Olenellus was once re- 

 garded as expressing the decadence of the Paradoxides 

 type, may not this suggestion of primitiveness arise 

 from the fact that the Olenellus fauna occurs in Cali- 

 fornia 5000 feet above these interesting strata? 



Mr. Grabau carries on the correlation to " Devonic 

 tinae," in a paper involving considerable labour. In 

 Mr. Girty's essay on the Pennsylvanian, we notice 

 (p. 125) one of the special points provided for us by 

 America, viz., the occurrence of beds with Prodtictus 

 giganteus in California, which can be correlated more 

 easily with the Carboniferous Limestone series of 

 Europe than with the eastern Mississippian (Lower 

 Carboniferous) series of America. Mr. Girty believes 

 that none of the Upper Carboniferous faunas of North 

 America are truly of fresh-water origin. Even the 

 Appalachian facies (p. 128) with Naiadites, contain- 

 ing as it also does Lingula and " Aviculipecten," 

 must at any rate imply brackish water. 



It is hardly profitable to indicate isolated passages 

 of interest in a book so full of condensed and well- 

 ordered information. As examples, we may mention 

 in conclusion Mr. White's sketch of the rise of the 

 Devonian flora (p. 140), with its hint of Archaeopteris 

 prevalent in the upper series throughout the world ; 

 Mr. Williston's account of the faunal relations of 

 early vertebrates; and Prof. Osborn's "correlation of 

 the Cenozoic through its mammalian life." Though 

 primarily intended for the speciaHst, these essays will 

 do much to bring new life into the teaching and 

 writing of British geologists who are willing to look 

 beyond the seas. G. A. J. C. 



THE ANALYSIS OF SYNTHETICAL DYES. 

 Tests for Coal-Tar Colours in Aniline Lakes : A 

 Review of the Coal-Tar Colouring Matters generally 

 used in the Lake Industry, and their Behaviour with 

 Distinct Chemical Reagents. By G. Zerr. 

 Authorised English edition by Dr. C. Mayer. Pp. 

 xii + 230. (London : C. Griffin and Co., Ltd., igio.) 

 Price I05. 6d. net. 



THE complex nature, as well as their ever-increas- 

 ing number, render the analysis of synthetical 

 dyes no easy matter. The work before us endeavours 

 to fill a vacant gap in analytical literature, dealing as 

 it does with the detection of a large number of these 

 compounds in aniline lakes. 



The book is divided into two parts. 



P.'irt i. takes account of the lakes which may be pre- 

 pared from more than three hundred coal-tar colours. 

 Tlu- author's experimental results uhl.iinid 1)\ a study 



NO. 2160, VOL. 86] 



of the action of selected chemical reagents (caustic 

 soda, sulphuric acid, and stannous chloride in 

 hydrochloric acid), and also of solvents (hot water, 

 alcohol, and acetic acid) on these lakes, are arranged 

 in columns, thus forming a series of tables, which 

 comprise the greater part of the book. More than four 

 hundred lakes are considered, and their behaviour to- 

 wards sunlight, turpentine oil, and varnish is also 

 mentioned in these lists. 



Part ii. indicates the methods of recognising the 

 various coal-tar colours in the lakes. Here also we 

 have a number of tables which are really analytical 

 schemes deduced from the results obtained in Part i., 

 and containing sufficient details to explain their use. 

 We have repeated some of the experiments mentioned 

 in Part i. and have found them satisfactory. The 

 author himself in Part ii. gives us three detailed 

 examples of analysis, which may well serve as models 

 in the investigation of lakes containing one or more 

 colouring matters. The book will no doubt prove a 

 trustworthy guide to those engaged in the analysis 

 of lakes, and also to others who wish to enlarge their 

 experience in the identification of synthetical dyes. 

 Its utility, however, may be enhanced by the addition 

 of a standard colour chart, which will more definitely 

 explain column iv. of Part i., and by a supplementary 

 column (in Part i.), which may include, whenever 

 possible, the constitutional formulae and systematic 

 names of the various coal-tar colours mentioned by 

 the author, together with any references relating to 

 patents. The translator has done his part well, bring- 

 ing the work up to date. 



It is to be regretted that the translator, before 

 issuing the book, had not worked out a similar table 

 of tests for the coal-tar colours which are manufac- 

 tured by English firms, as in its present form it dis- 

 tinctly tends to encourage the use of coal-tar colours 

 made abroad as against those made by our own 

 manufacturers. 



DOMESTICATED ANIMALS. 

 Domestic Animals and Plants: A Brief Treatise upon 

 the Origin and Development of Domesticated Races, 

 with special Reference to the Methods of Improve- 

 ment. By Prof. E. Davenport. Pp. xiv-h32i. 

 (Boston, New York, Chicago, and London : Ginn 

 and Co., n.d.) Price 5s. 6d. 



THIS volume, we are told in the preface, is intended 

 primarily for high and normal schools in the 

 United States, and also appeals more specifically to the 

 general student. Consequently, it is of the utmost 

 importance that the information it contains should be 

 thoroughly trustworthy. A survey of the sections 

 devoted to groups of animals with which I happen to 

 be more particularly acquainted shows, however, that 

 this is very far, indeed, from being the case. 



Take, for example, the statement on p. 96 that all 

 the varieties of domesticated pigeons "have been l>r< d 

 within historic times from the single primitive lonn, 

 the wild or passenger pigeon." That, in iliis astound- 

 ing statement, the author has not by accident written 

 passenger pigeon in place of blue rock, is maniliNl by 

 tlie tact ili.ii a figure of the former bird is given on 



