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recent text-book of over fifteen hundred pages, the avowed champion of the newer terminology, is certainly inconsistent.

The index is unusually satisfactory and, for the most part, free from the irritating multiplication of references. The possibility of obtaining the work in parts, either singly or as the complete set, will be appreciated by many.

The impressions of the new Morris as a whole may be summarized: As a description of gross anatomy the text is excellent and up to date, but in places too incomplete to afford an adequate presentation of the subject under discussion, unless supplemented by reference to other books. The illustrations are strikingly inharmonio,us. The numerous )cuts copied from other sources, especially those from Toldt and from Spalte- holz, have been reproduced, in many cases, with indifferent success and, too often, are distinctly inferior to the originals. Notwithstanding these defects, the editor and his collaborators are to be congratulated an the marked improvement of the new edition over the previous ones. In its revised form Morris will resume its honored place among the foremost text-books of anatomy.

George A . Piersol.

EVOLUTION OF fif-4JfMALI.m I lOL; IR TEETH to and from the Tri- angular Type, including collected and revised researches on Tri- tuberculy and new sections on the forms and homologies of the molar teeth in the different orders of mammals. By HENRY FAIR- FIELD OSBOEN, Sc.D., LL.D., D.Sc., edited by W. K. Gregory, M.A. New York: The Macmillan Company, 1907. Pp. i-ix+ 1-250, including bibliography, with 215 figures in the text.

The question of the evolution of the mammalian molar teeth is one which has interested comparative anatomists for many years, and it ia with great interest that the present work on this subject has been received. The work is essentially a technical one, intended for the very advanced student or for the specialist, since one who has had no great amount of training would be able to appreciate the book. The author‘s object in gathering together his scattered essays on the subject of the evolution of teeth is to present the subject more fully to those who do not accept the tritubercular origin for the mammalian molar. He claims that this disbelief is due partly to misunderstanding, but “chiefly to the fact that some of the most decisive and convincing paleontological evidence in support of the theory has not been clearly advanced.”

222 The Anatomical Record.

The book is conveniently divided into ten chapters, the first five of which are taken up with quotations and comments by the editor and author from the author’s original essays published between 1887 and 1907. The sixth chapter is devoted to a discussion of the geological succession of molar types. Chapter seven gives the types of molars found in the different orders of mammals. Chapter eight deals with the evolu- tion of the premolars, and is in a way a digression from the main object of the book. Chapter nine was written by the editor and is given up to a critical review of the objections to the theory of the tritubercular origin of the mammalian molar and to a discussion of other theories. Chapter ten is another digression entitled “Rectigradations in the Teeth.”

The beginning student will find the work of little or no value to him, since there has been no attempt to make the book useful to that classs of students. It iS intended primarily for the specialist. One searchea in vain for a figure to give a definite idea as to what all of the various cones, protocones, metacones, metalophs, etc., really are in the teeth of such an animal as a common dog or the horse. The author has presup- posed that his readers are nearly as well acquainted with the subiect as he iS himself. This will cause the book to be of less value than it might have been.

The theory of the tritubercular origin of the molar teeth of mammals was first proposed by Professor E. D. Cope in 1883, but during the time in which he wrote on the subject he confined himself to a discussion of the early forms from the lower Eocene. Later the subject was taken up by Dr. Osborn, and it was carried by him through successive stages of the geological development of mammals. Cope was first led to a consideration of the theory by observing that in the mammals from the Puerco Eocene the molars almost universally consisted of three cusps. The main cusp Cope postulated as the primitive reptilian cusp, and it has been named by Dr. Osborn the protocone. The lateral cusps arose aa outgrowths from the sides of the protocone, and are known respectively m the paracone and the metacone. From this simple three cusped type of molar Dr. osborn has traced homologies through nearly d of the orders of mammals. Opposed to this theory is the one advanced by Ameghino that the tritubercular tooth arose by the fusion of three reptilian cones. This is known aa the concrescence theory.

Studente of zoiilogy will be grateful to the author of the volume for inserting the outline of the classification of the mammals, whIch in-

The Anatomical Record. 223

cludes the living as well as the extinct forms. The table of classi5cation covers six pages, and it gives the latest results of the work of the author on the relationship of the various orders of mammals. On page 17 is given a diagram showing the stratigraphy of the mammal horizons of North America in their probable relations to each other.

The author was first led to a critical study of the tritubercular theory through his studies on the Mesozoic mammals, which have, for the most part, tritubercular teeth. The first chapter of the book is given up to a discussion of the molars of these Mesozoic mammals, and the original figures published by the author are reproduced here. The next chapter is given up to a general discussion of the development of the mammalian molar from the primitive tritubercular tooth, or, rather, from the primitive single reptilian cone, which is postulated but is not known. A deh i t e system of nomenclature is proposed for the various cones of the teeth. The primitive cone is named the protocone, and additional cusps are given names which distinguish their order of appearance or their position. To the names of the cusps of the teeth of the lower jaw the s a x id is attached. For instance, protoconid is the primitive reptilian cone of the lower jaw teeth. The author expresses the hope that the nomenclature will be retained, even if the theory is rejected, since the confusion which would result from another system of names would then be avoided. In the third chapter the author gives a discussion of the molars of

primates, which he has studied from the point of view of the trituber- cular theory. He is able to trace definite homologies in the teeth of the primates with the molars of more generalized mammals. The principles of the theory are here repeated in detail and some space is given to a discussion of the manner of ori& of the alternate c u s p of the upper and lower jaws. In the following chapter a discussion of the molars of ungulates is taken up and new terms are proposed for the various typea of ridges and cusps which the molars of these mammals exhibit. The ridges are spoken of as Zophs and we have the terms protoloph, meta- loph, etc., with the same meanings attached to the terms as in the caae of the more simple molars. The fifth chapter include8 a revised outline of what has been given in the preceding chapters. In chapter six is given a very interesting and instructive dimassion

of the chronological distribution of molar typea. The author agrees with most paleontologists that the Theriodontia were ancestral, or nearly so, to the mammals, and includes in hie discussion of the molars the

224 The Anatomical Record.

teeth of the theriodonts. The different reptiles described exhibit molar types which vary from the protodont or single cusp to the multituber- cular type in Tritylodon, although Dr. Broom has recently claimed that Tritylodon is a true mammal.

The next ninety-two pages of the book will undoubtedly prove to be of most value to the zoological student, since in these pages is given a discussion of the types of molars found in the various orders of mam- mals with the various cusps and ridges identified according to the tritubercular theory. There is only one thing that can tend to lessen the value of the work, and that is that the forms discussed are extinct. Little or nothing is said about the molars of living mammals. This part of the book is, however, a decided advance over anything we have in the literature on mammals. There is an abundance of good illus- trations showing the various types assumed by the different orders of mammals.

The chapter on the evolution of the premolars is based on the work of the author and on that of Dr. W. B. Scott. The evolution of the premolars differs from that of the molars in that the premolars of the upper and lower jaw do not seem to have followed the same line of evolution, although the form of tooth is not greatly different in the upper and the lower jaws. The same terminology may be applied to the cusps of the premolars as to the molars, although this has been disputed by some.

The remainder of the book, with the exception of a very few pages, is taken up by the editor in a discussion of the objections and diffi- culties in the tritubercular theory and a statement of the other theories for the evolution of the mammalian molar teeth. The editor is quite fair and candid in his statements, and one readily perceives that he has not allowed himself to be prejudiced by his belief in the trituberculsr theory. His statement of the other theories is quite fair and just. The theories in opposition to the tritubercular theory which have been advanced are the plexodont or concrescence theory first put forth by Ameghino, the embryological theory advanced by Taeker, Riise and others, and an entirely different interpretation of the elementa of the titubercular teeth of the Jurassic mammals as restudied by Dr. J. W. Gidley. The concresence theory is dismissed at once because there seems to be no basis to support it. The embryological theory is given more consideration, and it differs from the theory outlined by Osborn in the different ages assigned to the various cusps. According to

The Anatomical Record. 225

ontogeny, the paracone of the upper molars of Osborn arisea earlier than the protocone. Gidley’s restudy of the Jurassic mammala would seem to confirm the results obtained by the embryologists, and it may make necessary a revision of the tritubercular theory.

The work as a whole is an excellent one. The illustrationti are good, with the exception of those on page 43. The proofreading hae been well done, since there are but few typographical errors. The bibliography in the back will be useful. The book is well indexed and it cannot but be of much service to those interested in the development of the higher animals.

Roy L. Moodie.

A TEXT-BOOK OF STJRQICAL ANATOMY. BY W. F. CAMPBELL. Octavo of 676 pages and 319 illustrations. $6.00 in cloth, $6.50 in half morocco. W. B. Saunders Company, Philadelphia and London, 1908.

According to the author “the single purpose of this book is to aid the student and practitioner in mastering the essentials of tpractical anatomy,” and in many respects the work is well calculated to accomplish this end. M i l e lacking the cyclopedic fulness of many treatises on the subject, it must, nevertheless, in its own class, take high rank for the amount of valuable material presented and the manner in which it has been treated. Surgically we find it very complete and practical, the exposition clear and to the point, and those for whom it is intended will miss little of practical importance, although a somewhat fuller and more detailed treatment of certain topics, e. g., the eye and particu- larly central nervous system would have enhanced the value of these important chapters. Fortunately the writer is a teacher of anatomy, and his knowledge of the subject has enabled him to produce a work of corresponding anatomical accuracy upon which the practitioner can rely and in which the treatment of questions of pure anatomy is quite refreshing when compared with that of certain other text-books on the same subject. He has introduced a large amount of descriptive material on the more important regions, to which are added many well-chosen and instructive illustrations. Not only has normal anatomy in so far as it concerns the student been handled most commendably, but those variations and abnormalities which are of surgical or medical interest have received rather’ extensive attention.