4 INTRODUCTORY LETTER. 



free the intellect chained in the narrow bounds of artifi- 

 cial methods, we should early fix the attention of the young 

 naturalist on the universality of these views, and accustom 

 him to seize, at a single glance, all the features which, by 

 their union, form the peculiar character of each indivi- 

 dual. 



My ovm attempts, and the example of my predecessors, 

 have proved to me that the artificial metliod can be em- 

 ployed with less success in the reptiles than in other classes 

 of animals ; and that, in following such principles, we shall 

 never be able to give this science that clearness so essential 

 to the beginner. In the publication of my labours, then, 

 I lay down as a rule, to trace, in a few words, a faithful 

 portrait of each species, considered in its different relations 

 to allied species, to indicate the passage of one imaginary 

 group to another, and to reduce the science to its most 

 simple objects: such is the object of my classification. To 

 attain this end, without introducing innovations, I have 

 availed myself, as respects the nomenclature, of the materials 

 M^hich I have found in the works of my predecessors. I hope 

 that philosophers will agi'ee with me in this : for what me- 

 mory is capable of mastering the nomenclature of even a 

 single class of the animal kingdom, and of making it avail- 

 able in the study of Nature ? In what confusion have not 

 modern naturalists plunged the most beautiful of the 

 sciences, by erecting those unintelligible systems, the sole 

 merit of which often resolves itself into a mere parade of 

 words, which dazzle instead of enliglitenmg. Such systems 

 appear to me made only for their authors, and miss their aim, 

 which should be to guide the student, until he be tempted 

 to persuade himself that systems do not exist in natm^e. 

 Yet these modern artificial methods are not themselves 

 proof against a rigorous examination ; they are far from 

 having established what is meant by sj)ecies and genus. 

 Slight differences of form in some isolated part, due often 

 either to accident or to the influence of different climates, 

 have often induced naturalists to divide a species into sub- 

 species, and to designate each by a special epithet ; some 

 of these imaginary species united, form sections which they 

 are pleased to denominate sub-genera, although they are 



