THE PRIMARY TYPES OF FORM. 107 



type more widely diffused among nearly all the classes 

 of the animal kingdom, than that of the body being 

 mailed^, or protected, as in the chelonian reptiles, by 

 bony plates, either united or articulated at their su- 

 tures, or lying over each other in the manner of scales. 

 Wp have already cited numerous instances of this struc- 

 ture in the animal kingdom ; nor is it more conspicuous 

 in the chelonian reptiles than in the cheloniform fishes : 

 the family of the Balistidcs, in short, is as complete 

 a prototype of the tortoises, the hedgehogs, the scaly 

 anteaters, the porcupines, and other spined gliri- 

 form quadrupeds, as it is possible to conceive. Our 

 surprise is that such resemblances should exist where 

 the nature of the animals are so different. Again, the 

 smallest and most imperfectly formed mouths, destitute 

 of true teeth, are to be found among the Plectogna- 

 THES, or cheloniform fishes, which thus became the most 

 aberrant type in the great circle of Pisces. 



(96.) There is still a fifth primary form in the animal 

 kingdom, which has been designated the Rasorial type in 

 ornithology, and the Unguiculate among quadrupeds. 

 The characters by which this form may be recognised^ 

 among the animals just named, have been already so 

 fully explained, that they need only to be touched upon 

 in this place. In the more organised or warm-blooded 

 Vertebrata, great strength of foot, the faculty of climb- 

 ing, with a facility and aptitude for domestication, are 

 among the most prominent peculiarities observable in 

 this type ; but none of these can be expected in fish. 

 This is the type, however, which is so remarkable for 

 the great development of the tail; for, if we went through 

 the whole class of birds, and selected those, beginning 

 with the peacock, wherein the tail was most conspicu- 

 ous, either for its size, its length, its singularity, or for 

 the beauty of its colours, we should unknowingly fix 

 upon those birds which analysis has demonstrated to be 

 rasorial types. The same results would attend a similar 

 selection of quadrupeds, and of winged insects. All 

 these, collectively, furnish many hundred proofs by 



