XIV PREFACE. 



to others which perhaps are not inhabitants of this country ; 

 and that these and similar errors have arisen not merely 

 from the imperfect, but, it must be added, careless de- 

 scriptions which have been given of such animals, it is 

 hoped that the pains which have been taken to render 

 this portion of the work as complete and accurate as pos- 

 sible, will not be thought entirely thrown away. The plan 

 which the author has adopted in most instances, in the 

 case of the Fish especially, which of all our British Ver- 

 tebrata have till lately been the least attended to, and, 

 in regard to the distinction of species, the worst under- 

 stood, has been to describe as minutely as possible the first 

 species in each genus, or sub-genus if it present a marked 

 modification of form, and then, when there were other nearly 

 allied species, to restrict himself principally to the differences 

 which were observable in these last, with reference to the 

 first and to one another. By this method, which is adopted 

 from MM. Cuvier and Valenciennes, the enquirer is more 

 readily enabled to identify the particular species he may 

 have before him. In the Class of Birds, the different 

 variations of plumage, arising from age and season, have 

 been pointed out and characterized so far as they are 

 known ; and this plan has been pursued even in the case 

 of those species which have occurred in this country as 

 yet only in the immature state, for the more complete 

 guidance of our own naturalists, in the event of their being 

 met with in the adult plumage. 



What has been said of the descriptions applies also to 

 the measurements. They are to be considered as original, 

 excepting where the name of any author stands attached to 

 them. They have been taken with much care, in by far the 

 larger number of instances, from recently killed specimens, 

 and many of them are the mean results obtained from mea- 



