3o8 



NATURE 



u- 



;AivV 4. I'M- 



to the method of equal altitudes for the delermination 

 of latitude and time, and the application of this method 

 to the particular forms of observation for which th<- 

 instrument is luited. The problem of determining 

 jfeojfraphical lonfjitude is treated in the fourth chapter, 

 and forms m verv prrfty rxnmpir of nstronomical 

 geometry. 



The authors are not content with thu*; havinjj given 

 at length, yet tersely, the fullest instructions as to the 

 principle, the construction, and the use of their ad- 

 mirable device ; they now give complete directions as 

 to the preparation of the observations, the preparation 

 and use of tables in the reduction, jjraphical solntioiis, 

 and special cases. 



The second part of the book is eminently j.i ..i ... .tl, 

 in which actual operations are described, actual tables 

 given, and values from actual observations are repro- 

 duced. 



It will be seen that the manual is intended to leave 

 no question in reference to the astrolabe d prisma 

 unanswered, and the intention has been rigidiv fol- 

 lowed. For example, in any astronomical operation 

 the question as to the ease with which accidental 

 and instrumental errors may be isolated and eliminated 

 is a crucial one, and to this question MM. Claude and 

 Driencourt pay special attention. Possible, but not 

 obvious, imperfections in the glass of the prism are, 

 perhaps, the chief source of error ; therefore they make 

 the determination of the possible amount and action 

 of this error a special feature. 



•As to the practicability of the method and apparatus, 

 the book contains actual evidence in the observations 

 of the difference of longitude Paris-Brest, and in those 

 made by Lieutenant Mailles in delimitation of the 

 Congo and the Cameroons. In both cases was the 

 astrolabe A prisme employed, and in both cases were 

 results of the highest precision secured. 



The different types of instrument are well illustrated 

 1>v diagrams and reproductions at the end of the book. 



THE TEETH OF VERTEBRATES. 

 Vergleichende Analomie des menschlichcn Gebisses 

 find der Ziihne dcr Vertebraten. By Dr. P. de 

 Terra. Pp. xiv + 45 1 + 200 figures. (Jena: Gustav 

 Fischer, 191 1.) Price 12 marks. 



TO write a comprehensive treatise on the teeth of 

 vertebrates demands a familiarity with a very 

 wide range of anatomical, zoological, and especially 

 palaeontological literature (the book under review con- 

 tains a bibliography of about 3000 titles!), infinite 

 patience to master and assimilate it, and industrv to 

 arrange and set forth so vast a material in orderly 

 fashion. That this colossal task should have been 

 accomplished with some measure of success by a 

 dental surgeon reflects great credit upon the author 

 of this book, Dr. Paul de Terra, of Zurich. 



He describes his aim as an attempt to fill what has 

 hitherto been a serious lacuna in German literature, 

 namely, the lack of any book of the nature of the 

 English classic, Tomes's " Manual of Dental 

 Anatomy, Human and Comparative." 



He has also endeavoured to supply the generally 

 felt want of a detailed and systematic summary- of 

 NO. 2201, VOL. 88] 



th»' scattered literature embodying the results of recent 

 ff«warch in odontology-— a statement of the fact*, nn4 

 the theories put forward to explain them, in 

 manner as to suggest the phylogenetk: devcl 

 of teeth. 



Dr. dc Terra is of opinion that the time has 1..-. 

 arrived for compiling an adequate treatise upon t 

 comparative anatomy of teeth, because many of ' 

 most fundamental problems relating to the interj 

 tation of the arrangement, structure, and evoliiti<.ii 

 teeth are still in dispute. He has aimed, thri-;.!.. 

 at presenting^ an impartial - -of all the facts 



and the views of different ; • >. without com- 



mitting himself to any one explanation. A good 

 example of his mode of dealing with such disputed 

 problems is seen in his non-committal statement 

 (pp. 60-69) concerning the hypotheses of tritti*-'— •'■• 

 and concrescence. 



This attitude may perhaps commend itself to 

 expert reader and be useful to the teacher, who wrr 

 a detailed statement of the evidence for and 

 a particular view; but we think the student has . 

 to expect from the author of a treatise, who presi- 

 ably has a much more intimate acquaintance with • 

 evidence than even his writings reveal, some guida; 

 in picking his steps amidst the tangle of ^-"»--< 

 views. 



This book is really an encyclopaedia ot ci< i 

 anatomy: it deals in great detail with the comparat 

 anatomy of teeth, jaws, and skull, their min 

 structure, their developmental histor>'. and the disi 

 sions that have sprung from attempts to interpret 

 significance of their form and arrangement. It c 

 sists of an introduction, in which such general qi; 

 tions as nomenclature, general embryology, and / 

 logical classification are discussed, and three sectif 

 dealing respectively with (i) the comparative anatt>: 

 of the skull and buccal cavity in the \'ertebrata ; 

 the nature, composition, structure, and significance 

 teeth ; and (3) a detailed systematic account of i 

 teeth in all the vertebrate groups. 



The colossal bibliography is well classified; but it 

 includes a number of references to small handbo< 

 on general anatomy, zoology, and embn.-ology whi 

 might have been omitted with advantage. Moreo\' 

 one may search in vain in this list of literature 

 many of the most important memoirs on strictly dei 

 anatomy that the last decade has produced. Osbor 

 important treatise on mammalian teeth is a case 

 point. .Andrews's monograph on the evolution of 

 teeth in the Proboscidea, which is not mentioned, 

 perhaps of more importance than the whole of the 

 fifty-six works quoted in reference to this subject. 



There are also some curious groupings of mammals : 

 the Sirenia and Cetacea are included in one ordi^r 

 (Cetomorpha) and the Hyracoidea are included in tl 

 order Proboscidea ! 



No doubt it would be easy for the specialist to find 

 fault with much of the detail in a compilation such 

 as this. But the book will serve a very useful purpose 

 as a work of reference ; and the majority- of those who 

 will have occasion to consult it are not likely to be 

 led astrav by '*% inaccuracies or omissions. 



G. E. S. 



