192 ANNALS OF SCOTTISH NATURAL HISTORY 



boys or girls who show a leaning towards the pursuit of nature- 

 knowledge. 



A Treatise on Zoology. Edited by Sir Ray Lankester, 

 K.C.B., F.R.S. Part VIL Appendiculata. Third Fascicle: 

 Crustacea. By W. T. Caiman, D.Sc. Pp. viii. and 346. (London : 

 A. and C. Black, 1909.) Price 15s. net. 



The value to the general student of the accounts of the Crustacea 

 which have appeared almost simultaneously in three English text- 

 books, can scarcely be overestimated, for the need of an English 

 treatise dealing with this important class has long been acutely felt. 

 That the present volume has been written by so well-known an 

 authority as Dr. Caiman is a guarantee of thoroughness, and the 

 thoroughness is especially noticeable in his accounts of structure 

 and development, although enough is said regarding its definition, 

 zoological history, habits, palaeontology, and affinities, to render the 

 account of each group remarkably complete. 



Several changes from the classification adopted in most other 

 treatises are noticeable : chief of these being the suppression of the 

 comprehensive sub-class Entomostraca in favour of many sub-classes, 

 which, on account of their heterogeneity and negative characters as 

 a whole, cannot form a unity in a natural system. 



Throughout the volume are scattered facts of the greatest 

 interest to the general reader. Thus in the pages discussing the 

 morphology of the Decapoda we find striking examples of con- 

 vergence : as, for example, where a long eyestalk is due to the 

 lengthening now of the first segment {Podophthabiius)^ now of the 

 second {Macrophthalmiis) ; or again, w^here similar respiratory siphons 

 are developed in different families, at one time from the antennules 

 (Albunea), at another from their flagella {Sole?20cera), or again from 

 the fiagella of the antenna {Corystes). We learn that the truly 

 terrestrial Decapods, such as the Cocoa-nut Crab {Birgus)^ have 

 been derived from marine, and not, as would seem most reasonable, 

 from fresh-water types, and that, confirmed land-lubbers though 

 they appear to be, they pass their early stages in the ocean. 

 Interesting, too, are the references to "relict" faunas, otherwise 

 marine genera being represented in the now fresh-water areas of 

 N. Europe and America {Afysis relicta occurs in Ireland) — but we 

 note that no mention of them is made in the index. 



As in the whole series, binding and type are excellent, and the 

 volume is illustrated by numerous figures mostly adopted from the 

 original papers of recognised authorities. A valuable list embody- 

 ing the most important works deaUng with the group discussed is 

 appended to each chapter. — J. R. 



