INDIAN SNAKES. 



gradations of structure and organization separating them. 



Characteristics of the snake. A snake may be briefly 

 described as an apodal or limbless modification of the 

 vertebrate animal with an elongate body. Of course, 

 the most obvious and striking characteristic of a snake 

 is to be found in the nature of its organs of locomotion. 

 Our idea of progression in vertebrate animals is associat- 

 ed with limbs, or some modification of them ; in the 

 snake, however, we come to find a departure from this 

 established plan of creation. But to be able to properly 

 understand how, in the absence of limbs, the snake can 

 move about as freely as any other animal, we must have 

 some knowledge of its structure. An ardent student of 

 natural history will try to acquire this knowledge by 

 dissecting a snake and making himself familiar with its 

 anatomy, or, as the next best substitute of it, by visiting 

 the "Reptile gallery" of some museum. 



How does a snake mom in the absence of limbs ? A 

 glance at the skeleton of a snake will show that the ribs 

 take the place of limbs in the act of progression in the 

 snake. These ribs are very numerous, numbering more 

 than three hundred pairs in some species, and are 

 perfectly free at their extremities. Free, because, unlike 

 a great many other animals, there is no sternum or breast 

 bone in the snake. Being free and unattached, they are 

 also very movable. The free extremities of these 

 numerous and extremely movable ribs are attached to the 

 abdominal shields, or breast scales by elastic cartila- 

 ginous filaments. Another thing which renders the 



