330 NATURAL SCIENCE. May. 



small, dark, northern race L. calluna has any claim to be considered 

 a distinct species, pointing out, among other facts, that in Wales the 

 m3.\es oi L. calhine pair with females referable to typical L. guercus. 

 There are, however, instances of nearly allied forms, which, 

 though they interbreed where their ranges overlap, are considered 

 good species, e.g., the carrion and hooded crows. Mr. Barrett 

 gives a lively account of the "assembling" of male moths of L. 

 guercus around a captive female, " some flying steadily to the spot and 

 fluttering or running all over the place in which the female is hidden 

 ... or sweeping backwards and forwards in wide beats; while others 

 go quite frantic, dash themselves on the ground and spin on their 

 heads." There is also a vivid description of a flock of males trying 

 to cross the ridge of Hindhead in the teeth of a strong gale. Mr. 

 Barrett watched the moths work their way up a sheltered hollow 

 to the summit, only to be " instantly carried back over the valley, and 

 so tumbled ignominously down, to renew the strife with the same ill- 

 success." The student of bionomics will also find interesting matter 

 among the notodonts in Mr. Barrett's account of the protective 

 resemblance and mimicry of the " Puss " and " Lobster " moths — 

 Curtula vinula and Stauropus fagi — and their caterpillars, insects 

 rendered so familiar to naturalists by the writings of Professor 

 Poulton and other students of animal colour and form. 



There are only four genera of noctuid moths dealt with in the 

 present volume — Diphthera, Acronycta, Arsilonche, and A gratis. We are 

 glad to see that Mr. Barrett is going to favour us with a new classifi- 

 cation of the British noctuids ; the arrangement of genera with which 

 our entomologists have so long been content places closely-allied 

 species in different " families." Mr. Barrett writes wisely on the 

 difficulty of finding reliable structural characters for the differentia- 

 tion of these insects. They are a large and dominant family, pro- 

 bably still in process of comparatively rapid evolution, and hence the 

 difficulty which the naturalist experiences in dividing them up into 

 generic groups. In dealing with the Acronyct^, Mr. Barrett has 

 largely availed himself of Dr. Chapman's well-known studies of the 

 early stages. It is a pity that so few references are given to the 

 papers whence these and other particulars are taken, for one must 

 hope that some of Mr. Barrett's readers will wish to consult the 

 original memoirs. The next volume of the work will bring out the 

 author's views on the noctuids more fully. We notice that he 

 eschews names for varieties and aberrations in dealing with the very 

 variable species of the large and important genus Agrotis, but he gives 

 a succinct account of the principal types of variation in such species. 

 A. aguilina, by most recent students considered a form of A. tritici, is 

 retained by Mr. Barrett as a "good" species. In dealing with the 

 varieties of A. tritici, the author points out how the different forms 

 tend to " mimic " various species of Agrotis and other noctuid genera. 

 This fact is very suggestive as throwing light on the problem of 

 mimicry generally. In nocturnal insects like the agrotids, no advan- 

 tage to the individual can be supposed. But the fact that one species 

 may vary so as to resemble half a dozen others suggests a starting 

 point from which — in day-flying insects — one or more mimetic forms 

 might be preserved and the rest eliminated by the action of natural 

 selection. 



As in the previous volumes, the specific descriptions of the moths 

 and their preparatory stages are very good. We notice with regret, 

 however, that synoptical tables such as Mr. Barrett gave in his 

 early volumes are altogether wanting in the present one. The 



