Traité de Zoologie Concrète

Abstract

THE volumes of the “Traité de Zoologie Concrète” already published are so well known and have been so acceptable to zoologists that the present volume, dealing with the Cœlenterata, scarcely requires any recommendation. While it leaves little to be desired in such important matters as abundance and excellence of illustrations, bibliography, index and glossary, the chief merit of the “Traité de Zoologie Concrète” must be attributed to the logical and systematic method of exposition adopted by its authors. The majority of zoological text-books, following the German model, give a brief and insufficient definition of each class or order of the animal kingdom, and this is succeeded by a discussion of the organology and embryology of the class or order that is generally so diffuse as to leave the student in a state of hopeless uncertainty as to what are the characteristic structural features of the group in question. Recognising the importance of fixing clear and definite ideas of structural relations in the student's mind, MM. Yves Delage and Hérouard have adopted the time-honoured plan of illustrating the anatomy of each important group of animals by a description of a morphological type, which serves as a standard to which all the other members of the group may be referred. The method is familiar enough, but has fallen into discredit because previous authors have made too little use of it and have confined themselves to the description of one or two animals as examples of a large class, whence it has resulted that students have too frequently formed narrow conceptions of animal structure and have underestimated the wide range of variation of which animals belonging to the same class are capable. The “Traité de Zoologie Concrète” has the merit of having avoided this error by describing a morphological type, not only for each class or subclass, but also for each order, suborder, and even for each tribe. Thus a general description is given of the morphological type of the order Octanthida (Alcy-onaria); Kophobelemnon is taken as a type of the suborder Pennatulidæ; Renilla, Umbellula, Kophobelemnon, Pennatula and Gœndul are taken as the morphological types of the five tribes into which the Pennatulidæ are divided, and a sufficient description of the families and genera included in the tribe follows the description of each type. This system is consistently adopted throughout the work, and as the types are illustrated by well-designed schematic drawings, the essential characters of all the subgroups are brought in the clearest possible manner before the mind. Traité de Zoologie Concrète. Par Yves Delage Edgard Hérouard. Tome ii., 2me Partie, Les C"lentérés. Pp. x + 848. (Paris: Libraire C. Reinwald, 1901.)