PREFACE. Vll 



four only are described in Johnston, — the rest of his species being 

 either synonyms or resting on insufficient evidence. Fifty-four 

 British species have been examined by myself, perhaps a larger 

 number than have come under the notice of any other naturalist ; 

 by far the greater part in life and health ; and thirty-four of 

 these have been added to the British Fauna by myself. 



A new feature in works of this sort, which will strike the 

 student, perhaps needs a word of explanation ; — I mean the dis- 

 tinguishing of the prominent varieties of each species by a 

 diagnosis, and the assigning of a trivial name to each. Consider- 

 ing the variability of many of the forms, I trust the convenience 

 of this procedure will excuse the innovation. 



The analytical tables of the families, genera, and species, 

 hitherto scarcely known in English zoological works, will, I 

 think, be found useful ; nor will the attempt to tabidate the 

 geographical distribution of the species be devoid of interest to 

 the philosophic student. 



The plates must speak for themselves : they have been printed 

 in colours by Mr. W. Dickes, who has spared no effort to make 

 them, as nearly as possible, fac-similes of my original drawings, 

 which were made from the life. 



Nearly two years have been occupied in the progressive publi- 

 cation of the work, as it has been issued in bi-monthly parts. 

 Advantages and disadvantages attend this mode of publication. 

 Among the former may be reckoned that the information is 

 brought down to the latest period, and that the successive parts 

 stimulate the zeal and co-operation of fellow-labourers ; the book 

 thus embodying the knowledge of many, rather than of one. 

 Among disadvantages must be put down, incongruities between 

 the earlier and the later portions, statements made and opinions 

 hazarded which are subsecpiently corrected, and omissions which 

 are finally supplied. For these defects the author must cast 

 himself on the kind consideration of his readers, who must be 

 aware that no branch of science is at one stay even for a single 

 month. 



