126 Bibliograjihical Notices. 



expanding what is usually condensed iuto one or two volumes, the 

 work of a single author, into a series of volumes, each the work of 

 one or of several authors, as circumstances demanded ; and to this 

 end he applied himself to the task of selecting his team. The 

 signal success which ha's crowned his efforts lays us all under a 

 debt of gratitude, and at the same time demonstrates his knowledge 

 of " who's who " in the zoological world. 



Dr. Caiman's volume on the Crustacea will be welcomed not only 

 by carcinologists, but also by teachers conducting classes of ad- 

 vanced zoology, for no other group of Invertebrates, perhaps, is so 

 well suited to demonstrate the broad principles of morphology. 

 Dr. Caiman, himself a teacher of no small experience, has evidently 

 kept this aspect of work always before him, and thus his volume 

 will attain its fullest measure of usefulness. 



Having a wide and extensive knowledge of this group, the bulk 

 of what he has written may be regarded as first- hand information, 

 even though much of it may now be common knowledge ; but 

 where he had to rely 0:1 the work of others he has displayed a wise 

 discrimination. 



The pages of this book may be made to yield a helpful guide as 

 to lines of further research, for the author has indicated many 

 matters which need clearing up, somo of quite exceptional interest. 

 What, for example, is the nature of the spiue in Argidus, which is 

 generally regarded as a poison-organ ? This spine is provided with 

 a duct communicating with three large groups of unicellular glands 

 lying at its base. Though the secretion of these glands is generally 

 regarded as of a poisonous character, no definite evidence on this 

 head seems to have been adduced. Having regard to the universal 

 absence of ciliary organs in the Crustacea, it is of more than 

 ordinary interest to find in one of the Copepoda — the freshwater 

 Hepacticid Bdisarius — " a curious vibratile organ .... connected 

 with, or in close proximity to, the maxillary gland," which i3 " sup- 

 posed to be of the nature of a ' flame-cell.'" It is generally supposed 

 that retrogression, once it appears, must be continuous ; but the 

 author shows that, in the Crustacea at any rate, this is not onlv 

 untrue, but, among larvae, organs which have disappeared may 

 re-develop in later stages, as in the case of the thoracic part of the 

 male larva of Enterognatlius, one of the Copepoda. The develop- 

 mental history of this group shows yet other curious phases shared 

 in common with other lowly types belonging to it, in relation to 

 sexual characters. 



Finally, we may refer to the supposed occurrence of " hypodermic 

 impregnation " in the Asellotan Jcera, wherein it is believed that 

 " a spermatophore is inserted by the male between the thoracic 

 terga of the female, and that it permeates the articular membrane 

 and passes into the body-cavity, discharging its contents into the 

 oviduct, while the empty capsule is expelled by the oviducal aper- 

 ture." The account of this extraordinary process, Dr. Caiman 

 remarks, cannot be accepted without further investigation. 



