PKEFACE. 



With this volume is brought to a conclusion a series of works 

 ■which all zoologists must acknowledge to be of primary importance 

 in the history of science. The series consists of nine volumes, 

 viz.: — The Catalogue of Batrachia Salientia, published in 1882; 

 the Catalogue of Batrachia Gradientia, also in 1882 ; the Catalogue 

 of Lizards, vol. i. 1885, vol. ii. 1885, vol. iii. 18d7; the Catalogue 

 of Chelonians, Ehynehocephalians, and Crocodiles, 1889 ; and the 

 Catalogue of Snakes, vol. i. 1893, vol. ii. 1894, and vol. iii. 1896. 



These works are not only catalogues in the ordinary sense of the 

 largest general collections of Batrachia and Eeptilia ever yet brought 

 together, but are complete monographs of the groups of animals 

 treated of, so far as their zoological characters, geographical distri- 

 bution, and synonymy are concerned — descriptions being given of 

 every species regarded by the author as vaUd, whether contained 

 in the Museum or not. 



The initiative of the series is due to Dr. Giinther. It was begun 

 and has been carried out almost to its close under his Keepership 

 of the Zoological Department. 



Of the unremitting devotion of Mr. Boulenger to the task which 

 has occupied him for more than fifteen years, or of the ability and 



