92 species of NortJi American Tortoises. 



servations on these errors, will be affixed to those species to 

 which they apply. 



With the exception of Trionyx, the name of the old Lin- 

 nean genus Testudo has been retained, because 1 could not con- 

 scientiously adopt any of the modern divisions which have been 

 proposed. The monstrous absurdity which runs through 

 these is as shocking to all natural method, as it is insulting to 

 common sense. Taking Merrem's division as the newest and 

 most approved, what can we think of the Testudo Muhlen- 

 bergii being separated from the genus Emys, and placed in 

 what he calls Chersine ; again, who would have dreamed of 

 uniting the Testudo clausa with the T. pensylvanica and T. 

 odorata ; and what is still worse, making an accidental variety 

 of the last species, which belongs to his Terrapene, a different 

 genus, Emys ? Can a system which admits of such absurdities, 

 be conformable to nature or to sense ? 



Were I to propose a division of these animals into different 

 genera, it strikes me that the following would bo the most 

 natural : 



First. — Such as have the sternum furnished in a greater 

 or less degree with wings which are a prolongation of the 

 pectoral and abdominal sections, and joined to the chest by 

 bony commissures : these wings are generally supported on 

 each side by a smaller bony process, furnished with a plate, 

 which may be termed the supplementary plate of the wings. 

 The marginal plates are twenty-five, and the sternal twelve. 

 This would include the Chersine of Merrem, (Testudo of 

 others,) and the Emys ; but if all the species of the former 

 have the two caudal marginal plates united into one, as is the 

 case in the only species which we have, this character, joined 

 with the indistinct toes and the terrestrial habit, would separate 

 it from the other. 



Second. — Such as have the sternum joined to the shell by 

 bony commissures, but the supplementaiy plates interposed be- 

 tween the shell and the wings, the sternum generally (in 



