274 NATURAL SCIENCE [April 



characters and affinities of the Vermidea, a review of the range of 

 variation in the anatomy and physiology of the group, and some useful 

 synoptic tables of the classification. Finally, there are a bibliography, 

 an index to technical terms, a list of the hosts of the parasite forms, 

 and an index to the genera described in the volume. 



Throughout the book the style is fresh and interesting, the 

 descriptions lucid, and, considering the immense amount of detail 

 dealt with, very accurate. It may be pointed out, however, that the 

 " tentacles " of Sipunculus do not form a simple circle round the 

 mouth as described and figured on pages 12 and 16. They are the 

 lobes of a horse-shoe-shaped fold — probably a lophophore in fact — a 

 matter of some importance. The description of Sternaspis is neither 

 as accurate nor as up-to-date as we should like to see it. Considerable 

 vagueness prevails with regard to the nomenclature of the excretory 

 organs and genital funnels. Whatever may be the authors' opinion 

 concerning the homology of these organs (and we hope it will be 

 much more clearly expressed in subsequent volumes), surely the term 

 "organes" and " entonnoirs ser/mentaires " is singularly inappropriate 

 when applied to the nephridia or genital funnels of such unsegmented 

 animals as the Rotifera and Polyzoa. On the whole, the descriptive 

 part of this volume seems to us excellent, and bears witness to the 

 great industry and ingenuity of the authors. Particularly clear and 

 well illustrated are the accounts of such complicated processes as the 

 budding in the Bryozoa and the development of the Ectoprocta. 



Let us now turn from the purely descriptive to the more general 

 parts of the volume, those parts which deal with the classification and 

 affinities of the animals under consideration. Here Messrs Delage 

 and Herouard seem to us to have been much less fortunate. In the 

 class Bryozoa, for instance, the authors still include the Entoprocta, 

 although they are naturally enough unable to construct a real " type 

 morphologique " common to the Entoprocta and the Ectoprocta or 

 Bryozoa proper. It is difficult indeed to see how with any amount of 

 ingenuity they could possibly synthesize these two groups which 

 differ in every essential of their structure. Whilst in the typical 

 Ectoprocta, as is well known, a lophophore bearing hollow tentacles 

 surrounds the mouth, there are no nephridia, and the coeloni forms an 

 extensive body-cavity communicating with the exterior by genital 

 funnels ; in the Entoprocta we find a ring of solid tentacles encircling 

 the body so as to surround both mouth and anus, a substantial 

 parenchyma in which lie a pair of true flame-cell nephridia, and the 

 coelom is represented by a small pair of genital sacs opening by two 

 funnels to the exterior. True, budding occurs in both groups, and 

 in both the larvae have a more or less vague resemblance to a 

 trochosphere ; but the buds are of different nature, and what group of 

 Invertebrate Coelomata is there the larva of which does not bear a 

 certain likeness to a trochosphere ? Moreover, recent researches have 

 rendered very probable the view that, whilst the Ectoprocta are fixed 

 on their ventral surface, Pedicellino. lies, so to speak, on its back. In 

 this case even the nervous uanglia of the two forms would not be 

 homologous. Taking all these things into consideration, we fail to 

 see what excuse can be found for placing the two groups under one 

 name. 



