EXAMPLES OP CONNECTION BETWEEN ORDERS. 



59 



legs very short, and such Serpents as have the rudiments of legs 

 existing in the skeleton, but concealed beneath the skin in the 

 living animal. Of these, the common Blind- worm, or Slow- 

 worm of this country, is a cha- 

 racteristic example ; for so 

 completely does it blend the 

 characters of the Lizard and 

 Serpent tribes, that it has been 

 placed by some Zoologists in 

 one, and by some in the other. 

 With the Frog tribe the class 

 of Serpents is connected by a 

 very interesting animal the 

 Ccecilia, or Blind Snake; which 

 has the general form of the 

 snake tribe, but which, in fact, 

 really belongs to the order 

 Batrachia, having a skin des- 

 titute of scales, and being 

 found to undergo a metamorphosis, having at one period (like 

 the Frog, &c.) the same form of the circulating and respiratory 

 organs as the Fish. 



FIG. 15 NAIA ASPIC. 



FIG. 1C CHALCIS. 



40. But the order Batrachia is not connected with the other 

 tribes of Reptiles by one link of transition only ; for it contains 

 animals which may be regarded as representing the Turtles and 

 Lizards in its own group, just as the Bats represent Birds, and 

 the Whales represent Fishes, among the Mammalia. Thus, 

 there is a species of Frog in South America, whose back is covered 



