1594 The Zoologist— March, 1869, 



like hairs, feathers and scales, but are as permanent and durable as 

 the bones themselves. This may be seen when the slough of a snake 

 is found. This slough is continuous, and contains a faithful mould of 

 each of these processes : it is a very beautiful and very instructive 

 object. The tortoise exhibits the peculiarity of an articulated skin, 

 the articulation being clearly discernible in the living animal, but 

 becoming more conspicuous after death ; when dehiscence takes place, 

 and the plates fall off, perfectly detached from each other. 



Reptiles are further distinguished from sucklers and birds by their 

 generally colder blood, and from fishes by the possession of a neck 

 susceptible of being bent at an angle with the body ; by the absence 

 of a lateral line ; and by their mode of breathing, reptiles in their per- 

 fect state breathing by nostrils and lungs, fishes by the mouth and 

 gills. Fishes, moreover, breathe water, or rather the air contained in 

 water, reptiles breathing the atmospheric air. The breathing of 

 fishes is rythmical, that of reptiles irregular and capable of long 

 suspension. 



Reptiles have a less equable temperature than sucklers or birds, the 

 heat of their bodies being more under the influence of atmospheric 

 changes. Nature secures the well-being of the bird by providing it 

 with a thick clothing of feathers which maintain some degree of uni- 

 formity iu the temperature of the body ; but the reptile is preserved by 

 a diti'erent arrangement, the temperature of its body rises and falls 

 with that of the surrounding medium. Tlius reptiles are rarely seen 

 abroad in cold weather or in cold countries : their languid circulation 

 does not enable them to resist the increased cold, and very many, on 

 the approach of winter, bury themselves iu sand, gravel or mud, or 

 conceal themselves in the hollow of trees or under fallen leaves, and 

 become apparently lifeless. 



Compared with sucklers and birds, all reptiles seem apathetic as 

 regards their young ; that fierce care which is the characteristic of 

 both those classes has few examples among reptiles ; and this is one 

 of those natural rules which seern proved rather than invalidated by 

 the occasional exceptions : thus when we hear of a jnthon incubating 

 her eggs, or a toad carrying her little ones in the cavities of her back, 

 we say at once, " How extraordinary ! what a striking exception to 

 the rule." In this, as in every investigation, we must lake facts 

 as we find them, and never presume to define what ought to be the 

 course pursued by Nature in her infinitely various arrangements for 

 the perpetuation of her creatures. 



