lxiv PRELIMINARY SKETCH OP THE 



where a more permanent character can be found. 

 The form "of the tail, whether even, cuneated, 

 or forked, is used by him as a distinguishing 

 character. In the parrot-genus he uses it ac- 

 cording to its greater or less length than that 

 of the body. In others the colour of the beak, 

 a naked or a crested head, serves as distinctive 

 marks. On others nature has stamped some 

 peculiarity by which they are immediately 

 known; such as the receptacle of the lower 

 mandible in the Pelican, two long tail-feathers 

 in the Tropic-bird, tyc. One very frequent 

 mark is the difference of colour in the quill- 

 feathers and those of the tail. 



We now proceed in our account of the Lin- 

 naean system to the third class, called Am- 

 phibia ; but we shall, for the sake of brevity, 

 dispense with any further enumeration of ge- 

 nera. Of this class there are two orders. 



Order I. — Reptilia. Furnished with feet, and 

 breathing through the mouth. 



Order II. — Serpentes. Destitute of feet, and 

 breathing by the mouth. 



The generic characters of this class are taken 

 from the general figure of the body, from the 



