April 15, 1898.] 



aOIENCE. 



537 



■effected in practice ; it is, indeed, one of the 

 merits of the book that it is capable of a con- 

 siderable degree of modification in actual use to 

 adapt it to different conditions of instruction or 

 to differences of view regarding classification. 

 On the whole, the new text-book deserves a 

 warm welcome, and while not sufficiently ex- 

 tended to take the place of some of the larger 

 manuals, such, for example, as Lang's fine 

 treatise on comparative anatomy, we believe it 

 will be found an invaluable aid not only to 

 special students of zoology, but also to a large 

 number of those whose main interest lies in 

 other branches of scientific study. Written 

 with a clearness, accuracy and method that 

 bespeak the practiced teacher, it is admirably 

 illustrated with a profusion of figures — there 

 are nearly twelve hundred in all — of the highest 

 excellence. A large proportion of these are 

 original ; they are often of an artistic merit 

 rarely attained in text-books ; they are almost 

 without exception clear, yet are rarely schema- 

 tized. In all these respects the book offers a 

 model which cannot be too highly praised. 



E. B. W. 



Traits de zoologie, publiS soms la direction de 

 Raphael Blanchard. XVI., Mollusqvies, par 

 Paul Pelsbnebe; XI., Nemertiens, par 

 Louis Joubin. Paris, Eueff et Cie. 1897. 

 8vo. Illustrated. Pp. 187 and 59. 

 The present work comprises 24 pages of 

 general introduction, followed by chapters on 

 the five molluscan classes adopted, two pages 

 on phylogeny and an appendix of two pages on 

 the problematical Bhodope, which the author re- 

 gards as forming a subdivision of the Flat- 

 worms. Each chapter comprises a general dis- 

 cussion of the anatomy taken up by successive 

 groups of organs, followed by a synopsis of the 

 develoi)ment, habits and classification. 



The work consists chiefly of a rearrangement, 

 with some additions, of the material in the 

 author's ' Introduction a 1' etude des mollusques,' 

 published in 1892 in the Annales de la Societe 

 Eoyale Malacologique de Belgique.* Like that 

 work, it contains a useful compilation of the 

 principal data on the anatomy and develop- 

 ment of mollusks, more or less biased, as to in- 

 *Tome VII., quatr. sir., pp. 31-243. 



elusions and omissions, by the author's personal 

 views in regard to sundry contested topics. 

 While all the advances of the last six or eight 

 years may not be chronicled, the general dis- 

 cussion contains for the gastropods and amphi- 

 neura a fairly complete summary of current 

 opinion relating to the recent members of these 

 groups. In the case of the Peleoypods the 

 author adheres to the views introduced by him 

 some years ago, and omits to mention the facts 

 which have been put on record since that time, 

 which, to say the least, have rendered his 

 speculations decidedly less probable than they 

 at first 'appeared to be. The treatment of the 

 Cephalopods, from the ignoring of data fur- 

 nished by paleontology, is the least complete of 

 all. 



In the matter of classification the work is 

 hardly up to the level of criticism, and would 

 have gained in strength and dignity if the 

 feeble and unequal attempts at systematic ar- 

 rangement had been entirely omitted. Of the 

 most important advances in the systematic study 

 of mollusks during the last few years, such as 

 Pilsbry's work on the Pulmonata and Chitons, 

 Hyatt's contributions to the developmental 

 knowledge of extinct Cephalopods, or Bernard's 

 researches on the development of the hinge in 

 bivalves, this treatise contains not the slightest 

 trace. On the other hand, the useful work of 

 indicating to the student the lines on which 

 research is most needed, or likely to prove 

 fruitful, has not been attempted. The illustra- 

 tions are clear and good, though most of them 

 are familiar. It can hardly be claimed that the 

 occasional dabs of color add much to their value. 



Joubin's work on the Nemerteaus seems to be 

 a satisfactory and well written summary of our 

 knowledge of this interesting group. The illus- 

 trations are particularly good, and the author's 

 style is attractively clear. He accepts the 

 classification of Burger as on the whole the most 

 precise and natural. The paper concludes with 

 an interesting discussion of the relations of the 

 group to other worms, in which the conclusion 

 is reached that they are very closely allied to 

 the Turbellarians, with which (including the 

 Cestodes and Trematodes) they constitute the 

 order of Plathelminthes. 



W. H. Dall. 



