NOTE-BOOK OF A NATURALIST. 237 



giant forms of the boas aud pythons, which, deprived of 

 the stiletto of the smaller snakes, are recompensed with 

 an herculean power of gripe that would make the ribs 

 of an Antieus crack like pistol-shots, as they broke under 

 the pressure of the mortal constriction. 



Before we enter into a particular account of these forms, 

 let us inqiure what a reptile is. 



In common parlance the word would signify any 

 creature that creeps ; but, in the language of zoologists, it 

 is used to designate those vertebrated animals, whether 

 quadruped, biped, or footless, that are either oviparous 

 or ovoviviparous, breathe by means of lungs for the most 

 part, are destitute of hair and feathers, and are without 

 mammas. 



Their organization, although designed after the one 

 great law which is manifested throughout the vertehrata, 

 is more variously modified than that of any other class 

 of that division of animals. If we examine the mam- 

 malia we find them formed after one leading type. 

 From man to a marmoset, from a lion to a cat, from an 

 elephant to a mouse, from a whale to the smallest 

 cetacean that swims, the same plan of construction is 

 manifested. Among the feathered race, from an eagle 

 to a humming-bird, from a dinornis to an apteryx, we 

 recognise an adherence to one settled principle of con- 

 formation. It is the same with fishes. But among the 

 reptiles, a wide and extensive difference in the types or 

 principles of structure must instantly strike the most 

 superficial observer. A tortoise and a snake are both 

 reptiles, zoologically speaking. Look at these animals 

 alive, or examine -their skeletons, and a glance shows 

 you the wide difference of conformation displayed in the 

 two forms. But without selecting types so obviously 

 distant, we shall find similar discrepancies, external and 

 internal, in this extensive class, and that even among the 

 more cognate reptihans. Take a crocodile, an ichthyo- 



