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THE genus TODUS evidently succeeds the last. As 

 it is one of them which are typical of this sub- 

 family, we should expect to find it more numerous 

 in species and more diversified in forms; and such we 

 discovered to be the case. Unlike the three aberrant 

 divisions we have just quitted, the one before us 

 presents us, for the first time in this family, with a 

 complete and perfect circle, where scarcely a link 

 is missing; and where we have, in consequence, 

 the five types of nature fully and perfectly demon- 

 strated. Hitherto we have been barely able, with 

 much difficulty, and some latent doubts, to make 

 out the prominent types of the divisions just gone 

 through ; not so much from the absolute relations 

 which they bear to each other by intervening spe- 

 cies, as by comparing our distribution of the order 

 of their succession with that of other and more 

 perfect circles, whose validity has been long esta- 

 blished. But in the todies we can proceed with 

 more confidence ; for if, amidst so much variation, 

 we can yet establish the same uniformity, and add 

 another instance in corroboration of those general 

 laws else>vhere promulgated, additional confidence 



