OUR LIVING WORLD. 



REPTILES. 



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

 Reptiles, or creeping animals, are spread over those portions of the globe 

 where the climate is tolerably warm, and are found in the greatest profusion 

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

 temperature of such freezing chilliness that any of the higher animals would 

 perish under its severity, and for the most part being lovers 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 very soil appears to teem with their 

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

 roughly indicated by the parallels of latitude, the lands near the equator being 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 

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

 water, and are able to pass a considerable time below the surface without requiring to 

 breathe. 



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

 of their blood is effected. 



As has been shown in the two volumes on Mammalia and Birds, the heart in these animals 

 is divided into a double set of compartments, technically termed auricles 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 where the 

 oxygen obtains a freer access to its particles. 



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

 from that of the higher animals. Dull sluggishness seems to be the general character 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 terrific frenzy by love, rage, or 

 hunger, their ordinary movements are inert, their gestures express no feeling, and their eyes, 

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

 general habits of their bodies, and the process of digestion is peculiarly slow. 



Most of the Reptiles possess four legs, but are not supported wholly upon them, their 

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

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

 the fixing squirrels; and in former days, when Reptiles were apparently the highest race on 

 the surface of the earth, certain species were furnished with wing-like developments of limb 

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



