May 12, 1898] 



NATURE 



27 



the so-called " Salinella " of Frenzel as though some 

 evidence worthy of attention had been produced in sup- 

 port of the existence of such a creature ; and they declare 

 that a species of Apus " has been shown to be " herma- 

 phrodite. They allude to the assertions of Mr. H. M. 

 Bernard. It is well that that gentleman's attention should 

 be drawn to the fact, and that he should at once either 

 withdraw or confirm by some evidence his published 

 statement that a species of Apus is hermaphrodite. 



As to faults of omission — there is no doubt always room 

 for divergence of opinion as to what should and should 

 not be comprised within the area of a book necessarily 

 selective and limited. But nothing can, it seems to me, 

 justify the omission of all reference to the important 

 Leeoh, Acanthobdella^ when the affinities and origin of 

 the Hirudinea are discussed ; nor such an inadequate 

 account of the tubular continuations of the pericardial 

 ccelom of Lamellibranchs as that which is given at 

 p. 640, where Keber's organ is treated as an excretory 

 organ, and nothing said of its morphological significance. 



Opinions, no doubt, may differ as to the exact form and 

 spelling of many zoological terms. At the same time, I 

 fail to see the justification for writing "ccElome" in the 

 place of "ctt;lom,""Coelenterata" in place of " Coulentera," 

 and " Echinodermata" in the place of " Echinoderma." 



It will thus be seen that although there is a great deal 

 of excellent description in the new "Text-book," and 

 many beautiful and useful figures, there is yet a very 

 serious amount of inaccuracy, and in some matters of 

 great importance a want of sound judgment which must 

 seriously interfere with its utility. 



It is not uninteresting to compare with the text-book 

 of Parker and Haswell, one of the four text-books of 

 icoology which are in course of publication at the present 

 moment in France. We have that by Prof. Delages and 

 M. Hdrouard, also a text-book by Prof. Edmond Perrier 

 of comprehensive scope and abundant detail ; one edited 

 by M. Raphael Blanchard, to which a whole series of 

 authors contribute each his fascicle ; and one by Prof. 

 Roule, of Toulouse. The work projected by Prof. 

 Delages is the most original of these, on account of the 

 method pursued. Prof. Delages aims at a complete 

 logical exposition of the characters of each phylum^ 

 class, order, family and genus of the animal kingdom. 

 Not only that, but he gives a schematic figure which 

 corresponds with his description of each group — so that 

 the student realises in concrete form the characteristics of 

 a class —an order or a family — characteristics which may 

 be modified by greater or less development, but give the 

 essential features of the group. Hence the term 

 "Zoologie Concrete," which forms the title of the work. 

 The plan is a carrying out into a complete system of the 

 method which I (borrowing it from older writers) made use 

 of when in my article Mollusca (" Encycl. Brit."), I drew 

 an Archi-mollusc. Prof. Delages will, when he comes to 

 that group, draw and describe not only an archi-mollusc, 

 hut anarchi-gastropod, archi-cephalopod, &c., and also an 

 archi-prosobranch, an archi-diotocardian, and an archi- 

 patellid, and similar schematic forms — " types morpho- 

 Jogiques," as he terms them — for every group — down to 

 the actual genera. It is essential to the plan of Prof. 

 Delages' work that every genus shall be not only named 

 NO- 1489, VOL. 58] 



and cited, but described at sufficient length to enable the 

 reader to identify the genus of a specimen concerning 

 which he is interested, and thus to obtain a reference to 

 more detailed monographic literature. 



It is evident at once that the project is a very large 

 one. Such a work fully carried out with complete an- 

 atomical detail such as is necessary to give a true concep- 

 tion of the relations of large and small groups, would be 

 an ideal treatise for the advanced student. The only 

 objections to it seem to be (i) that if thoroughly done it 

 must be a work of enormous size, extending to at least 

 twenty large octavo volumes. (2) That it is impossible for 

 one or even two authors to possess a sufficiently detailed 

 knowledge of the whole animal series to produce a really 

 accurate and judicious account of every group with the 

 minuteness proposed. 



We have, however, two volumes already published— 

 the first dealing with the structure of the Cell and with 

 the group Protozoa, the second devoted to what MM. 

 Delages and Herouard call the "Vermidea," namely 

 certain small groups of debated affinities ; to wit, the 

 Gephyrasa, Polyzoa, Rotifera, ChcCtognatha, Kinorhyncha 

 (Echinoderes), and Brachiopoda — names which Prof, 

 Delages prefers to alter into Gephyria, Bryozoaria, Tro- 

 chelmia, Kinorhynchia and Brachiopodia. Some of the 

 changes in names and the classification adopted by 

 MM. Delages and Herouard (especially in regard to the 

 Protozoa) are valuable and likely to secure general assent. 

 But it is difficult to approve of the word Vermidea 

 — a Greek adjective made from a Latin substantive — 

 and one which, to me at any rate, seems not to be 

 necessary for classificatory purposes. 



In these two volumes we can see how the " concrete ' 

 system of exposition works. It certainly results in a 

 very useful treatise on the Protozoa. Numerous process 

 blocks (no less than eight hundred and seventy) are 

 introduced into the text, and though they are by no 

 means equal in beauty to the woodcuts of the text-book 

 by Parker and Haswell, they are yet sufficient for their 

 purpose. In the second volume published (that on the 

 Vermidea), which is vol. v. of the series as planned by 

 Prof. Delages, forty-five coloured plates are introduced 

 as well as five hundred and twenty cuts. Many of the 

 coloured plates are occupied with diagrammatic figures, 

 showing by means of strong conventional colounng the 

 anatomy of Gephyrseans, Rotifers, Polyzoa and Brachi- 

 opods, but two are devoted to highly-finished coloured 

 drawings of the living appearance of selected species of 

 Sipunculids and Echiurids respectively. It is probably 

 the first time that a treatise intended for students has 

 been so fully illustrated. Naturally, in attempting to 

 test the quality of such a book, one looks at the treat- 

 ment of subjects specially familiar to one's self. In this 

 volume I looked with curiosity at the account of Rhabdo- 

 pleura. I find it excellent, occupying eight pages, with 

 seven large process blocks— some coloured, which are 

 diagrams, others copied from originals duly acknowledged. 

 The only objection I have to offer is that here as else- 

 where the authors yield to a very natural tendency, and 

 instead of using the terms " tubarium," " pectocaulus," 

 and " gymnocaulus," as applied to certain parts in the 

 original description from which their information is 



