THE REPTILES AND AMPHIBIA. 361 



5. Grallatores, Waders, or Stilt birds. 



6. Palmipedes, or Web-footed birds, now more generally recognised 



as Natatores, or Swimmers. 



It has been proposed to separate the Brevipennes, or 

 short-winged birds, from the Grallatores, and erect them into a 

 separate order. 



The Reptiles, of which the majority possess the faculty of 

 living upon land and in water, whence their name of 

 Amphibia, never pass beyond the limits of warm and 

 temperate climates : their blood, which has the same tem- 

 perature as the medium wherein they live whence their 

 name of "cold-blooded animals" does not circulate where 

 the mean annual temperature descends below freezing-point. 

 Yet frogs and salamanders have been met with in Greenland, 

 and on the banks of the Mackenzie River, in North America, 

 under 67 latitude. 



Linnaeus was not acquainted with more than 215 species 

 of Amphibia, divided into four orders : the Chelonians, or 

 tortoises; the Saurians (as the lizard and crocodile); the 

 Ophidians (serpents); and the Batrachians (frogs). In 1789, 

 Lacepede raised the total to 303 ; in 1820, Merrem estimated 

 it at 677. At present, the number of species of Reptilia 

 classified and described amounts to 2000, and the four 

 orders into which they are distributed are 



1. Ophidia, or Serpents. 3. Loricata, or Crocodiles. 



2. Sauria, or Lizards. 4. Chelonia, or Tortoises. 



