THE RASORIAL FORM IN QUADRUPEDS. 259 



ox, the former were to have horns, and the latter a flow-f 

 ing tail, how closely would they resemble each other ! 

 On such principles, that beautiful and astonishing va- 

 riety, which constitutes one of the most remarkable 

 features in the creation, would be destroyed; and if 

 each type were to exhibit all the properties or peculiar- 

 ities theoretically belonging to it, we should have but 

 five unvaried forms of living beings. This is the rock 

 upon which many naturalists, who have not sufficiently 

 reflected on the subject, are continually splitting. They 

 argue after this fashion : How can you maintain that a 

 bat represents a mouse or a wading bird, when the first 

 has wings, the second none, and the third has but two 

 long legs ? or, how can you draw up a set of characters 

 purporting to belong to the rasorial type, when many of 

 the animals you bring forward in support of your 

 theory are actually without some of these characters ? 

 Such reason ers appear to forget, that if a mouse had 

 wings, it would be no longer a mouse it would be a 

 bat ; while the analogy of these quadrupeds to a wading 

 bird, from being very remote, must not be made an im- 

 mediate object of comparison, but must be traced through 

 a number of intermediate analogical forms. 



(318.) The economy and instinctive dispositions of 

 the rasorial type are stamped with many remarkable 

 circumstances, deserving our deepest attention. So 

 little, however, is known of such invertebrated animals 

 as come under this denomination, that we must, in the 

 following observations, be understood to speak more 

 particularly of the rasorial types of quadrupeds and of 

 birds ; thus selecting our illustrations from the most per- 

 fectly organised, and the best known, of vertebrated 

 animals. The economy of this type is in direct oppo- 

 sition to that of the natatorial; for it is strictly ter- 

 restrial : we know not, in fact, a single instance where 

 the individuals belonging to it frequent water or its 

 vicinity. This propensity to live removed from that 

 element does not, however, confine these animals to the 

 bare ground ; for they either walk upon the surface with 

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