336 Mr. Burnett's Illustrations of the Quadrupeda, 



Illustrations of the Quadrupeda, or Quadrupeds, being the 

 arrangement of the true four-footed Beasts indicated in 

 outline, 



Tetrapoda, Quadrupeda, the originals of our naturalized 

 Tetrapods and Quadrupeds, words formerly synonymous, and 

 equally translatable four-footed, have, however, in the progress 

 of science, become appropriated to different meanings ; and this 

 is one of the advantages which our language gains by engraft- 

 ing into it classic terms ; for shades of difference are thus 

 succinctly and elegantly expressed without a periphrase ; an 

 important power, of which dialects, less mixed, are utterly un- 

 conscious and devoid. 



The earlier naturalists, to whom little more than the external 

 structure of animals was known, and by whom dissections 

 were but seldom practised, consequently selected for their 

 zoographic signs the most obvious features of exterior form, 

 such as the wings, the feet, the claws, the teeth, &c, aided, 

 when observation failed them not, by the habits of the several 

 grades. Hence the Tetrapoda of the Greeks, and the Quadrupeda 

 of the Latins, were terms literally and indiscriminately applied, 

 and included the four-footed reptiles, along with the four- 

 footed beasts. The frog, the toad, the tortoise and the croco- 

 dile were associated, in one compartment, with the lion, the 

 deer, the elephant and the mouse ; the two series being inter- 

 distinguished as the oviparous and the viviparous sections. Yet, 

 as further investigations shewed, not only that these were more 

 or less clothed with hair, while those were invested with scales, 

 or naked ; but also that the one had warm blood and a double 

 heart, the others a single heart, and varied in their tem- 

 perature with the medium around them ; that the former were 

 more nearly allied to serpents, and the latter to whales, than 

 either to each other : the number and developement of the 

 feet proving fallacious, as a primary distinction, was very pro- 

 perly eschewed ; and other less defective means proposed and 

 followed in their stead. 



The discovery of a proper circulation, which threw so much 

 light on the animal economy, and solved so many problems in 

 physiology, had its influence on physiography likewise ; and 



