June 30, 1904] 



NA TURE 



195 



though by no means exclusively attached to them, and 

 are consequently very liable to be carried from one 

 country to another. But it is rather startling to read 

 in the preface, 



" The number of species found within the British 

 Isles is eightv-eight, with four varieties; of this total, 

 fiftv-one species and two varieties have been found 

 living under glass, and have undoubtedly been intro- 

 duced from other countries. A few of these aliens have, 

 .ipparently, existed in this country as plant pests for 

 more than half a century ; while others have been intro- 

 duced within the last fifteen years, and with the ex- 

 ception of a few species, have apparently come to stay, 

 and add to the difficulties of plant-culture." 



The males are small delicate insects, and the females 

 are apterous, and are sometimes ornamented with 

 elegant laminated appendages of wax, as in the species 

 of Orthezia, which are not uncommon on grass, 

 nettles, and other low plants. It must not be forgotten 

 that although the Coccida; include such destructive 

 insects as the American blight and the San Jos6 scale, 

 other species furnish us with some of the most useful 

 products obtained from insects, such as cochineal, lac, 

 &c. It remains to add that Mr. \ewstead has given 

 us a very full account of the transformations, habits, 

 i\;c., of each of our British species, and that the plates 

 are e.xcellent. 



There are few more useful, and at the same time few 

 more injurious, families of insects than the Coccidas, 

 and also few which have been so much neglected by 

 entomologists until within the last ten or fifteen years, 

 though latterly they have been so much studied by good 

 observers in most parts of the world that our know- 

 ledge on the subject has advanced by leaps and bounds. 

 Thus, in 1891, only seven species of Coccidse were re- 

 corded from Ceylon, but Mr. Green took up the study 

 immediatelv afterwards, and in November, 1894, he 

 was already able to enumerate not seven, but seventy- 

 two distinct species which he had observed up to that 

 date. In the preface to the present work, dated 

 September, 1896, he says : — 



" This large number will be almost doubled in the 

 present work, . . . and when other parts of the island 

 have been properly explored, it is probable that con- 

 siderably over two hundred species will be recognised." 



It is needless to say that such estimates usually prove 

 to be very much below the mark. The three parts of 

 Mr. Green's book already published include ninety-one 

 species, belonging to three subfamilies out of eleven 

 (Conchaspinas, Diaspinae, and Lecaniinas, of which last 

 only the genus Lecanium is at present monographed), 

 and nine genera, besides preface, glossary of terms, 

 introductory and supplementary chapters on habits, 

 classification, remedial measures, &c. We are not told 

 how many more parts will be required to complete the 

 work, and it is possible that Mr. Green himself cannot 

 at present decide, for there will no doubt be large addi- 

 tions required to the earlier portions. He appears to 

 have done his work very completely and thoroughly, 

 and the illustrations are excellent. Respecting these, 

 Mr. Green writes : — 



" The lithographic plates, reproduced from my own 

 drawings, have been most carefullv printed in colours 

 by P. W. M. Trap, of Leiden." 



NO. 1809, VOL. 70J 



We are pleased to see that Mr. Hudson is continu- 

 ing his efforts to make the small, but highly interest- 

 ing, insect fauna of New Zealand more widely known, 

 and we hope he will continue to deal with other orders- 

 in succession. As in other groups of animals, the 

 Neuroptera exhibit the usual characteristics of the 

 fauna, a very small total number of species, a striking 

 absence of most of the characteristic Australian groups, 

 and the presence of a very few remarkable species- 

 peculiar to New Zealand. .Among the latter we may 

 mention the handsome dragon fly I'ropetala Carovet 

 (named by .\dam White after the author of the " Story 

 Without an End "), which superficially resembles our 

 British Cordulegaster annulatus, Latr. , but is larger. 



Mr. Hudson describes the early stages of many of 

 the species he notices, and figures several larvje and 

 pupae in addition to the perfect insects. In an appendix 

 he discusses the food of trout in New Zealand, founded 

 on an examination of the contents (chiefly insects) of 

 sixty trout stomachs. On the other hand, the larvse 

 of some of the larger Neuroptera may (like those .of 

 Dytiscus among the Coleoptera) be destructive to 

 fish. Thus we read (p. 5), " The larva of Stenoperla 

 prasina, Newm., might perhaps prove destructive to- 

 very young fish." 



The Mallophaga and Psocidae are not included in the 

 present volume, and the Embiidje and PanorpidEe are 

 unrepresented in New Zealand. We have thought a 

 comparison of the number of species of the families 

 dealt with by Mr. Hudson, found in Britain and 

 New Zealand respectively, might be interesting : — 



Families Britain 7^P"', 



Zealand 



Termitidse (White .\nts) o ... 3 



Perlida; (Stone Flies) 24 ... j 



Odonata (Dragon Flies) 40 ... 10 



Ephemeridae (May Flies) 37 ... 13 



.Sialidaj (Alder Flies) 2 ... i 



Hemerobiid;E (Lace-winged Flies) ... 48 ... 8 



Phrvganeidje (Caddis Flies) 136 ... 24 



W. F. K. 



DARWINISM AND THE STATE. 

 La Concurrence sociale et les Devoirs sociaiix. By 



J. L. de Lanessan. Pp. 308. (Paris : F^lix Alcan, 



1904.) Price 6 francs. 

 lY/r DE LANESSAN has added yet another to the 

 ■ many books that undertake to show the work- 

 ing of Darwinian principles among civilised races, and' 

 this, like so many other books dealing with the same 

 subject, shows no real knowledge of Darwinism. The 

 author is strongly anti-Darwinian, and maintains that 

 the struggle for existence leads to degeneration in the 

 labouring class, which finds itself over-matched in the- 

 struggle against an aristocracy or a plutocracy. 



At the outset some clear definition is needed. 

 \A'hat is meant by degeneracy? Apparently our 

 author means the under-development of the individual 

 through defective nourishment and unhealthy con- 

 ditions generally. This is, no doubt, a great evil, but 

 it is not racial degeneracy. Would M. de Lanessan 

 deny that the physical strength of civilised peoples is 

 maintained by the large amount of elimination that 

 still goes on? (In England nearly 50 per cent, of the- 

 population die before the average age of marriage,. 



