March i, 1900] 



NATURE 



419 



competent to judge of them, or to estimate their relative 

 value and importance, unless he himself has a practical 

 as well as a theoretical acquaintance with the subject. 



One disadvantage in collecting Dragonflies is the diffi- 

 culty of preserving the colours of most of the species. 

 Hence the importance of carefully coloured illustrations 

 taken from fresh specimens ; and although Mr. Lucas's 

 illustrations, which appear to be colour-printed, are not 

 equal to Charpentier s beautiful plates of the same in- 

 sects, they represent the insects very well, and the neu- 

 ration of the wings is also accurately reproduced. 

 Photography would, however, be the only way in which 

 the neuration of many of these insects could be produced 

 with absolute accuracy, especially in the case of Neuro- 

 ihemis and one or two other East Indian genera, in 

 which the network is excessively fine, and must include 

 thousands of divisions in each wing. 



Mr. Lucas has divided his work into nine chapters — 

 introduction, life-history, classification, the nymph, the 

 imago, genera and species, reputed species, breeding the 

 nymph, and preparing for the cabinet. The book con- 

 cludes with addenda and corrigenda, list of works re- 

 ferred to, and a good general index. There are also 

 detailed tables of genera and species, and even of the 

 nymphs. The plain figures represent oviposition, eggs, 

 nymphs, parasites, and various details of the insects. 



In order to show the full manner in which Mr. Lucas 

 has dealt with his subject, we will take one of the best 

 known, though not one of the very commonest species, 

 Libellula quadriinaculata, Linn., to which nearly twelve 

 pages are devoted. First we have synonymy, then the 

 original description (which we would gladly see inserted, 

 as a matter of course, in all descriptive works, whenever 

 possible, as it would save much misunderstanding and 

 inaccuracy), size, description of the male imago, the 

 female, immature colouring, variation, oviposition, ^%^, 

 nymph, emergence of imago, date, habits, migration and 

 distribution within the British I sles. It might be sug- 

 gested that notes on .extra-British distribution, and when 

 desirable, notes on allied non- British species, would 

 have made the account of each species more complete. 



L. quadrimaciilata is the most remarkable of the 

 European Dragonflies for its migratory habits, and if 

 memory serves us, it has sometimes been observed 

 migrating in company with butterflies, though whether 

 pursuing them as prey, or whether both species were 

 urged by some common impulse, may be a matter for 

 investigation. Most Dragonflies, except the slender- 

 bodied and delicately-formed Agrionidte, are very strong 

 on the wing, and many even of those which are not 

 migratory in their habits are often met with a long way 

 from water. But there is no doubt that many Dragon- 

 flies are habitually migratory, which may partly 

 account for the wide distribution of other species besides 

 L. quadrimaculata, which latter, it may be noted, is 

 found throughout temperate Asia and North America, as 

 well as in Europe. In Christmas Island, near Java, 

 where three wide-ranging species of Dragonflies are 

 found (one of them being the almost cosmopolitan 

 Pantala /lavescens, already referred to), they are never 

 seen except when the wind is blowing from a certain 

 direction, when they appear suddenly in swarms. 



A century ago we had no systematic works on British 

 insects at alL except Lewin's admirable book on British 

 Butterflies, published in 1795 : fo*" even Marsliam's pioneer 

 book on Coleoptera, and Haworth's on Lepidoptera, did 

 not begin to appear till the beginning of the present 

 century. .\t present we have more or less complete 

 works on several orders and families of insects ; but 

 there are still many large groups, including the great 

 order Diptera, and a large portion of the orders Hymen- 

 optera, Xeuroptera, and some families of Homoptera, of 

 which we have no adequate up-to-date monographs at 

 all, at least in a separate form. 



NO. 1583, VOL 61] 



We congratulate Mr. Lucas on his having so success- 

 fully filled up one of these remaining gaps in our British 

 entomological literature. 



As a specimen of Mr. Lucas's style, we may quote his 

 account of the habits of one of the commonest of the 

 larger British Drao^onflies, /Eschna cyanea, Miiller : 



" Though sometimes seen flying over the water, where 

 it is difficult to catch, this insect is oftener met with 

 along hedgerows and lanes, where it sometimes for a 

 long time flies backwards and forwards over a very re- 

 stricted range. On such occasions, notwithstanding its 

 rapid, powerful flight, it is usually possible, with careful 

 watching, to make a capture. When once startled, how- 

 ever, it usually soars away out of sight, to return very 

 possibly, however, to the same spot a little later. On 

 one occasion, in Berkshire, I noticed an .E. cyanea 

 hawking along a hedge in this way, and presently saw it 

 capture a butterfly (probably the Small Copper). After 

 circling round it several times the Dragonfly secured its 

 prey, and began wildly careering round as if rejoiced at 

 its success. While thus engaged, a wing of the butterfly 

 ^or part of one — was let fall, and cyanea settled in the 



'Eschna grandis ovipositing. 



hedge, where it appeared to be further stripping its 

 captive. Shortly after, the Dragonfly was captured in its 

 turn, when the body of the butterfly was found still be- 

 tween its jaws. But it is, of course, not at all an un- 

 common thing for one of the larger Dragonflies to capture 

 a butterfly, whose wings it removes in a very workmanlike 

 manner." 



Apropos of the above passage, we may remark that a 

 large North American Dragonfly {Anax longies^ Hagen), 

 belonging to the same family as ^-Eschna cyanea^ is de- 

 scribed as habitually decapitating; its prey, which generally 

 consists of some of the larger butterflies. W. F. K. 



NOTES. 



The desire has been widely expressed in University circles 

 in Edinburgh that the Curators of Patronage, with whom the 

 appointment to the chair of medicine rests, should offer the 

 post to Prof. Osier, of the Johns Hopkins University, who is 

 well known as a teacher and clinicist of the highest scientific 

 eminence, and whose acceptance of it would greatly strengthen 

 both the systematic and clinical teaching in the University. It 

 would appear, however, that the Curators have no choice in 

 the matter, but are bound to advertise every vacancy, so that 



