242 NATURAL HISTORY. 



repulsive feeling to the mind, which is not felt on examining any other animal. In confinement, the 

 general stillness of most, and the slow crawling motions of some of these creatures, stamp the whole 

 with the title of creeping things, or reptiles. And when they are in their natural homes, where some 

 display an activity of a singular and occasionally rapid kind, the word creeping is so very generally 

 true to nature that the tarm reptile really does convey the difference between them and the other 

 vertebrated animals. No one can confound any of these creatures with any of the Mammalia. 

 Most observers of birds would object to their pets being compared with a reptile, and would say that, 

 althoxigh the claws and scaly legs of many a bird are not without resemblance to those of the 

 crawling things, there can be no satisfactory comparison between them and the feathered tribes. 

 There is no difficulty in distinguishing between most fish and the reptiles. 



Common experience, then, without troubling itself about the insides of the creatures, has 

 separated those whose names were mentioned at the commencement of this chapter from the other 

 animals with vertebrae or back-bones. Beasts, birds, fishes, and reptiles used to be the great 

 divisions of the Vertebrata. 



A visit to a collection of living or dead reptiles impresses one with the great number of kinds 

 there are of them, and how very varied ai*e their shapes and peculiar gifts. Some have limbs, others 

 have not ; some have a skin, most are scaled, and a few have a regular armour. They live on land 

 and in fresh and salt water, and some indulge in a kind of flight. Some begin life in the water, and 

 end it on dry land. If they are really to be divided from the other Vertebrata, it must be acknow- 

 ledged that there are greater differences amongst them in shape and in method of life than there are 

 in any of the other classes already noticed. 



Very early in the history of comparative anatomy it was shown that the reptiles, popularly 

 so-called, were cold-blooded, like fish, and that it was necessary, principally from the method of life 

 in their youth, or on account of the changes which occur in the anatomy and physiology of their 

 breathing apparatus during their growth, to separate them into two groups : the reptiles, to which 

 belong the Tortoises, Crocodiles, Lizards, and Serpents ; and the Amphibia, which in many instances 

 lead at some time of their existence an aquatic life, and which may have tails, like Newts (Tritons), 

 or which begin life with a tail, and lose it during growth, like the Frogs and Toads. 



The Reptilia, or Reptiles, are cold-blooded animals, with back-bones, which have a scaly or 

 bony-plated skin, which breathe by lungs, and whose heart has the ventricles not completely separated. 

 They have a single occipital condyle to the back of the head, and they may lay eggs or produce 

 living young. The existing reptiles are divided into several orders, some of which were represented 

 in the ages of the past. They are the Chelonians, or Tortoises ; Crocodilia, or Crocodiles ; Saurians, 

 or Lizards; Ophidia, or Snakes.* 



ORDER CHELONIA. THE BUCKLERED REPTILES. 



Tortoises, Terrapins, and Tui'tles are familiar objects of natural history, and belong to an order of 

 the reptiles called Chelonia. t These Chelonians are cold-blooded, four-footed reptiles, protected by 

 a case, buckler, or shell, and without te3th in their jaws, and they are thus distinguished from all 

 other animals. They usually lead monotonous lives, are numerous in individuals, and there are many 

 genera and families of them. They are divided into four great divisions, and they frequent land, 

 fresh water, and the sea. They have a great and remarkable geographical distribution, which, in 

 some instances, is very suggestive to the geologist and physical geographer, and one group (the 

 Turtles) is of commercial and gastronomic importance. 



As there are Land Tortoises, Fresh- water Chelonians, mud-loving-ones, and Sea Turtles, the 

 * This multiplicity of great divisions indicates that there is very great variety in the reptilian class of structure and 

 habits. It is also true that the kinds are very numerous, and that the genera are abundant. Many of the reptiles are never 

 observed by experienced naturalists, and it may be said with great truth that the knowledge of the habits of the group is not 

 so advanced as the knowledge of their anatomy. The classification of some of the genera is in dire confusion, the localities 

 whence some important kinds come are not decided, and unfortunately it is too true that the life history of many is quite 

 unknown. In the necessarily restricted space allotted to the reptiles in a work on natural history, which does not deal 

 with advanced anatomy or elaborate classification, it is only possible to describe and notice well-known or typical kinds ; and 

 in doing this the works of Cuvier, Owen, Giinther, Dr. Andrew Smith, Coues, Bell, Rymer Jones, Gray, and Huxley, have 

 been freely quoted, and often to the very letter. In making this acknowledgment, it is trusted that the accidental omission, 

 where such occurs, of the names of these distinguished naturalists will be forgiven. f Chelonia, Tortoise. 



