382 SNAKES. 



Hitherto the pit has certainly plagued not only zoologists, 

 but all classifiers of the Ophidia ; because serpents that have 

 this facial depression embrace so many widely differing 

 genera, some of them resembling in all other respects the 

 true vipers, and others the rattlesnakes, so that they have 

 come to be distinguished as the ' pit vipers.' 



One of our most able biologists, A. R. Wallace, in his 

 Geographical Distribution of A^iiinals^ informs us that 'the 

 CrotalidcB, including the deadly rattlesnakes, abound m.ost 

 in the oriental regions' (though not a single rattlesnake 

 is found there, or in the Old World at all). Let us seek for 

 the reason of this apparent incongruity, and how it is that 

 a large number of serpents which have no rattle come to 

 be placed among those which have an instrument specially 

 constructed to produce a rattling sound. 



Not to weary the reader by attempting to describe the 

 various systems of classification adopted by the many 

 herpetologists who were the contemporaries and immediate 

 successors of Linnaeus, we will rather invite his imagination 

 to picture the geographical history of our globe during that 

 age. Travels, explorations, the establishment of new colonies, 

 and the settlement of new territories marked the era ; and, 

 as a sequence, new and hitherto unknown fauna were con- 

 tinually brought home to Europe. We have seen, too, how 

 natural history had been growing into a science, and how 

 travellers and zoologists stimulated each other by their 

 researches and writings. To recall a few of the names 

 with whom reptiles are associated, and to remind the reader 

 that one arranged them according to their scales, another 



1 Ed. of 1876. 



