ipo4. 25 



REVIEWS. 



A SCIENTIFIC DIARY. 



Knowledge Diary and Scientific Handbook for 1904. Pp. 



108 -\- 420. London : Knowledge Office, 1903. Price ^s. net. 



It gives us pleasure to welcome again this useful and well-compiled 

 handbook, which now makes a regular yearly appearance, and cannot 

 fail to win the support of men of science generally. As usual, much of 

 the information given is concerned with Astronomy, Physics, and 

 Meteorology, but the articles on the Camera applied to Natural 

 History, by R. B. Lodge, and on some uses of the Microscrope, by 

 M. I. Cross, will appeal strongly to biological students. Readers of 

 Knowledge will regret the resignation by Mr. Cross of the editorship of 

 the microscopical columns of that magazine, but we are glad to learn 

 that his place will be taken by Mr. F. S. Scales, and that further space 

 will be devoted to the subject during 1904. 



INSECTS AND THEIR RELATIONS. 



On the Relationships between the Classes of the Arthro- 

 poda. By Gkorgb H. Carpenter, B.Sc, M.R.LA. Proc. R.I. A. 

 Vol. XX iv. (B) 1903. Pp. 320-360, pi. vi. 



The subject of Mr. G. H. Carpenter's paper on the relationship between 

 the classes of Arthropoda, concerns Irish zoologists as much as it does 

 those of other countries, though it does not deal with any peculiarly 

 Irish problems. It is a paper of very unusual merit which will, no doubt, 

 be widely read and appreciated by men of science. 



The views as to the origin and relationship of the Classes of Arthro- 

 poda, that is to say, of the Spiders, Centipedes, Insects, and Crustaceans, 

 are very divergent. Most zoologists however seem now agreed that 

 crustaceans and insects, at any rate, have developed on totally distinct 

 lines from annelidan ancestors. 



Mr. Carpenter takes a completely independent attitude in his argu- 

 ment that the various classes of the Arthropoda are truly related to each 

 other, and that they all must have had jointed-limbed ancestors. 

 From a comparative stud}^ of the morphology of the groups, supported 

 by some original and careful dissections of the minute anatomy of the 

 lowest Insects, and also from embryological and palaeontological evi- 

 dence, Mr. Carpenter is able to show an exact agreement in the number 

 of body-segments in the insects, the most primitive Myriapods, the 

 Crustaceans, and the Spiders. Hence he argues that these various classes 

 must be traced back to common arthropodan ancestors with a definite 

 number of segments, and that the views now generally current among 

 zoologists on the subject can no longer be maintained. 



R. F. S. 



