January 21, 1916] 



SCIENCE 



101 



The purpose of this voltime, as stated in the 

 preface, is " to bring together, in convenient 

 form for the use of students of zoology, some 

 of the more important details of the biology, 

 anatomy and development of the Crocodilia." 

 There are chapters on the biology of the Croco- 

 dilia, the skeleton, the muscles, the nervous 

 system, the vascular system, the urogenital sys- 

 tem, the respiratory system, the vascular sys- 

 tem, and the development of the alligator, and 

 a bibliography containing eighty-nine titles. 

 The book is illustrated by sixty-two figures, 

 about half of them original, and twenty-eight 

 plates, all but six of which are original. 



In the chapter on the biology of the Croco- 

 dilia, the classification and geographical dis- 

 tribution are briefly summarized, evidently 

 from general works, brief notes on the char- 

 acteristics of several forms are given, and 

 twenty-nine pages are devoted to a discus- 

 sion of the habits and economic importance of 

 Alligator mississippiensis, principally as re- 

 vealed in the writer's field work. The descrip- 

 tion of the muscular system is a translation 

 of Bronn's account of the muscles of Oroco- 

 dilus, with illustrations of the musculature of 

 Crocodilus and Alligator, and the description 

 of the nervous system is taken from Bronn and 

 others. The description of the digestive, ucro- 

 genital, respiratory, vascular and skeletal sys- 

 tems are original, as is the account of the 

 embryological development of Alligator mis- 

 sissippiensis, the last being a reprint, with 

 some alterations, of an earlier paper by the 

 author published by the Smithsonian Insti- 

 tution. 



The author has succeeded in his expressed 

 purpose of making the book detailed, and it 

 will at once find a place in the library of the 

 comparative anatomist and herpetologist as a 

 valuable reference work. In the opinion of the 

 reviewer, the only serious adverse criticism 

 which will probably be made by students is 

 that the chapter upon the embryological devel- 

 opment of the alligator is too detailed. A con- 

 nected and more readable account of the em- 

 bryology would be of more general value than 

 will be the monotonous descriptions of sec- 

 tions which make up this chapter. It is stated 



in the publisher's advertisement on the 

 jacket that the book " has an assured appeal 

 for the layman interested in natural history," 

 but this is doubtful, for, in addition to the de- 

 tailed treatment, the terminology is technical 

 and about seven eighths of the text consists of 

 descriptions of the anatomy and embryology. 

 Alexander G. Euthven 

 Museum of Zoology, 

 University op Michigan 



PROCEEDINGS OF THE NATIONAL 

 ACADEMY OF SCIENCES 



(Number 12) 

 The twelfth number of volimie 1 of the 

 Proceedings of the National Academy of Sci- 

 ences contains the following articles : 



1. Salts, Soil-Colloids and Soils: L. T. Sharp, 

 College of Agriculture, University of Cali- 

 fornia. 



New light is thrown upon the subject of salts 

 in relation with soil-colloids. The way is 

 opened for extensive experiments in the phys- 

 ical chemistry of soils, and the principles in- 

 volved will be of particular significance for 

 the subject of the applications of alkali and of 

 fertilizer salts. 



2. The Child and the Tribe: Alice C. 

 Fletcher, Peabody Museum, Harvard Uni- 

 versity. 



The rites connected with the initiation of 

 the child into the tribal life are described with 

 emphasis upon their significance in Indian 

 education and philosophy. 



3. The Correlation of Potassium and Magne- 

 sium, Sodium and Iron, in Igneous Bochs: 

 Henry S. Washington, Geophysical Labo- 

 ratory, Carnegie Institution of "Washington. 

 The author's earlier suggestion that soda 



not uncommonly tends to vary with the iron 

 oxides while potash shows similar relations to 

 magnesia is greatly strengthened by a compila- 

 tion of analyses of igneous rocks, numbering 

 nearly 10,000. 



4~Theorem Concerning the Singular Points 

 of Ordinary Linear Differential Equations: 

 George D. Birkhoff, Department of Mathe- 

 matics, Harvard University. 



