OUR LIVING WORLD. 



REPTILES. 



'HE remarkable beings which are classed together under the general title of 

 REPTILES, or creeping animals, are spread o\. -r those portiona of the globe 

 where the climate is tolerably warm, and an- found in the greatest profu*jon 

 under the hotter latitudes. Impatient of cold, though capable of sustaining a 

 temperature of such freezing chilliness that an\ <.f tin- higher animal- would 

 perish under its severity, and for the most |irt U-in^ liners of wet and swampy 

 situations, the Reptiles swarm within the regions near the equator, and in the 

 rivers or vast morasses of the tropical countries the v*-r\ soil apj>ears to teem with their 

 stnmire and varied forms. Indeed, the number of Reptiles to be found in any countrv is 

 roughly indicated by the parallels of latitude, the lands near the equator leing the most 

 prolific in these creatures, and containing fewer as they recede towards the poles. 



Some Reptiles inhabit the dry and burning deserts ; but the generality of these creatures 

 art- --mi aquatic in their habits, are fitted by their structure for progression on land or in 

 water, and an- able to jia-s a considerable tinu- l>elow the surface without requiring to 

 breath.-. 



This capacity is mostly the result of the manner in which the circulation and aeration 

 of their blood is eflWt-d. 



As has been shown in the two volumes on Mammalia and Birds tin* h-nrt in these animals 

 is divided into a double set of compartments, technically termed auric]** and ventricles, each 

 set having no direct communication with the other. In the Reptiles, however, this structure 

 is considerably modified, the arterial and venous blood finding a communication either within 

 or just outside the two ventricals, so that the blood is never so perfectly aerated as In the 

 higher animals. The blood is consequently much colder than in the creatures when- the 

 ..'en obtains a fr.-er access to its particles. 



In consequence of this organization the whole character of the Keptiles is widely different 

 from that of the higher animals. Mull sluggishness seems to be the general diameter of a 

 Reptile, for though there are some species which whisk about with lightning speed, and others, 

 especially the larger lizards, can be lashed into a state of t. -rriti.- frenzy by lore, rage, or 

 hunger, their ordinary mov.-m.-nts an- inert, their gestures exj-n n<> f.i-ling, and their eyes, 

 though bright, are stony, cold, and passionless. Their mode of feeding accords with the 

 p-ii'-i-il habits of their bodies, ami tin- process of digestion is jeculuirly slow. 



Most of the Reptiles possess four legs, but are not supported wholly uj-'ii them, th.-ir 

 bellies reaching the ground and being dragged along by th<- limbs. One or two species can 

 supjMirt themselves in the air while passing from one tree to another, much after the fashion of 

 the flying squirrels; and in former days, when Reptiles were apjarently the highest race on 

 the Mirface of the earth, certain species were funii-hil with wimr-like developments of limb 

 and skin, and could apparently flap their way along like the bats of the present time. 



