PREFACE. XV11 



Selby ; assistance has been also gained, in regard to the 

 situation of a few genera, from the system of Lesson *. 

 The arrangement of the Reptiles and Amphibious Animals 

 is for the most part in accordance with that in the " Regne 

 Animal" of Cuvier. The author has, however, followed 

 Latreille and many modern naturalists in considering these 

 groups as two distinct classes. The arrangement of the 

 Fish is likewise similar to that in the second edition of the 

 " Regne Animal," excepting a slight alteration in the value 

 of the larger groups, adopted from the Prince of Musig- 

 nano-f-. In no case must it be imagined that the order 

 of affinities is exactly the same as the order of arrange- 

 ment given, since, if it be true that all natural groups 

 be circular, an opinion now generally prevalent, and one 

 in which the author is strongly disposed to join, it is 

 clearly impossible to preserve such a coincidence under 

 circumstances which necessarily entail the appearance of 

 a linear series. 



The author has also exercised his own judgment in 

 the adoption of certain genera and sub-genera. With re- 

 spect to these last, having expressed his views elsewhere j, 

 it is unnecessary to repeat them in this place. He may 

 simply state that he has endeavoured to acknowledge, and 

 to act up to, the principle which he has there advocated ; 

 although, from the ignorance in which we are upon the 

 subject of the real value of many groups, it cannot be 

 doubted that numerous instances occur, in which he has 

 failed making a correct application of it. Being aware of 



* Traitt d' Ornithologie ; ou Tableau mtthodique des Ordres, Sous-ordres, 

 Families, Tribus, Genres, Sous-genres et Races d'Oiseaux. Par. 1831. 8vo. 



f Saggio di una Distribuzione metodica degli Animali Vertebrati. Rom. 1831. 

 8vo. The alteration above alluded to has been adopted by the author since the 

 publication of his " Systematic Catalogue/' 



Loud. Mag. of Nat. Hist. vol. vi. p. 385. and vol. vn. p. 97- 



b 



