NATURE 



THURSDAY, DECEMBER 23, 1909. 



THE CAMBRIDGE NATURAL HISTORY. 

 The Cambridge Natural History. Vol. iv., Crustacea, 

 by G. Smith and the late W. F. R. Weldon ; 

 Trilobites, by H. Woods; Introduction to Arachnida, 

 and King-Crabs, by A. E. Shipley; Eurypterida, by 

 H. Woods; Scorpions, Spiders, Mites, Ticks, &c., 

 by C. Warburton; Tardigrada (Water-Bears), by 

 A. E. Shipley; Pentastomida, by A. E. Shipley; 

 Pycnogonida, by Prof. D'Arcy W. Thompson. 

 Pp. xviii + 566. (London: Macmillan and Co., 

 Ltd., 1909.) Price 17s. net. 



WITH the present volume, the last to be issued 

 of the ten volumes forming the Cambridge 

 Natural History, that carefully planned and well- 

 executed work is completed. The editors, Dr. S. F. 

 Harmer and Mr. A. E. Shipley, are to be congratu- 

 lated upon having brought their enterprise to a satis- 

 factory conclusfbn, and upon having placed at the 

 disposal of advanced students of zoology, both pro- 

 fessional and amateur, an authoritative account of 

 each of the principal phyla of the animal kingdom. 



The section on the Crustacea had been entrusted 

 to the late Prof. Weldon, and the one chapter dealing 

 with the Branchiopoda, which he ' had completed 

 before his death, is so clearly the work of a master- 

 craftsman that it is hardly possible not to feel a 

 sense of regret that he was unable to finish the task 

 so well begun, and not to realise dimly what an 

 original and valuable contribution to crustacean 

 literature his completed work might have been. 

 Prof. Weldon's pupil, Mr. Geoffrey Smith, was placed 

 at a disadvantage in having to continue this work 

 at short notice and under pressure of time, and it 

 was not to be expected that he would be able to 

 carry it on upon the same lines as those on which it 

 had been begun. Where he is speaking of matters 

 with which his own researches have given him know- 

 ledge at first hand, Mr. Smith had done excellently. 

 Thus there is a very careful account of the order 

 Anaspidacea, and an even more interesting and sug- 

 gestive section on the parasitic cirripedes Peltogaster 

 and Sacculina, which infest other Crustacea. Other 

 portions of the section, which are clearly compiled 

 from the literature, are, unfortunately, not so satis- 

 factory, and there is great lack of a due sense of 

 proportion in dealing with many groups. Thus the 

 interesting order Cumacea is dismissed in about a 

 page and a half, and the information which is given 

 is so summarised as to be of little value. It cannot 

 but be a matter for regret, also, that in a work of 

 this character on the Crustacea so little attention 

 has been paid to internal anatomy. It is true that 

 much investigation is still necessary before a really 

 adequate account of the morphology of the internal 

 organs in this group can be compiled, but at the 

 same time a very large literature dealing with the 

 subject already exists which has been only very lightly 

 dealt with. 



Mr. Henry Woods contributes to the volume a 

 clear and well-illustrated account of the Trilobites. 

 XO. 2095, VOL. 82] 



He takes the view that their affinities are with the 

 Crustacea, more particularly with the Phyllopoda, and 

 recognises sixteen families. He is unable, however, 

 to accept either Salter's classification of the families 

 into four groups, or the modification of that classi- 

 fication proposed by Beecher. 



The principal chapters on arachnids are by Mr. 

 Cecil Warburton, who has written a very valuable 

 treatise on this group. Mr. Warburton's work is to 

 be especially commended in that he has done such 

 full justice to all aspects of his subject. The anatomy 

 and morphology of scorpions, spiders, and mites are 

 dealt with authoritatively and with great accuracy 

 of detail, whilst at the same time that side of the 

 subject which results from the work and observa- 

 tions of the field naturalist is treated in an equally 

 satisfactory way. Chapter xiv., dealing with the 

 habits of spiders, is, indeed, one of the most inter- 

 esting in the whole series of volumes of the Cam- 

 bridge Natural History. The subject is a fascinating 

 one in itself, and the author has, by a judicious intro- 

 duction of his own personal observations on familiar 

 British species, given to it an air of reality which 

 adds greatly to the pleasure of the reader and to the 

 value of the information given. 



Chapters on the king-crabs (Xiphosura) and on 

 Tardigrada (water-bears) and Pentastomida are added 

 by Dr. A. E. Shipley. With regard to the affinities 

 of the latter group of parasites, in which the struc- 

 ture is obviously much modified, the author does not 

 commit himself to any very definite opinion, but 

 contents himself with referring, in somewhat general 

 terms, to those characters which they possess in 

 common with some arachnids. A useful list is given 

 of all the known species, with their primary and 

 secondary hosts. 



The concluding chapter of the volume is by Prof. 

 D'Arcy Thompson, and deals with the Pycnogonida. 

 Prof. Thompson writes with somewhat greater 

 elaboration of literary style than is generally adopted 

 by present-day scientific authors, but whether always 

 with happy results we are inclined to doubt. Thus 

 the chapter opens with this sentence : — 



" Remote, so far as we at present see, from all other 

 \rthropods, while yet manifesting the most patent 

 features of the Arthropod type, the Pycnogons consti- 

 tute a little group, easily recognised and characterised, 

 abundant and omnipresent in the sea." 



The enthusiasm of the last clause of this sentence 

 would, we fear, be somewhat damped by a sudden call 

 to find, say, fifty living specimens in any but some 

 specially favoured locality. 



The chapter is, however, taken as a whole, clear 

 and accurate, and is certainly the best account of 

 the pycnogonids available for English students. 

 With regard to classification. Prof. Thompson con- 

 siders that Decolopoda is probably the most primitive 

 form known, and that Colossendeis is closely allied 

 to it. The Euryxydidae and Ammotheidse are allied 

 to Colossendeis, whilst the true position of Rhyncho- 

 thorax is very doubtful. On the other hand, the Nym- 

 phonidje, in 'which is included the five-legged Penta- 

 nymphon, described by Hodgson from the Antarctic, 

 also show a minimum of degeneration, and must, 



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