TPIE RATTLESNAKE 145 



which may have been such, predecessors. They were 

 gigantic, long-bodied animals, sometimes forty feet long, 

 with two pairs of limbs in the form of small paddles, and 

 a head somewhat like that of a python. They had jaws 

 which could be dilated to a certain extent like those of 

 serpents. But, as we have seen, it is not all snakes which 

 possess this power, and since these American giants must 

 have gained this power independently, it is difficult to see 

 why the serpents of later times may not have clone like- 

 wise. True and undoubted snakes, however, began to 

 make their appearance in the lower tertiary rocks. They 

 were mostly large-sized and seem all to have been non- 

 venomous, though a fossil viper has been discovered in 

 the middle tertiary rocks of the south of France. 



Among living reptiles we can hardly expect to find the 

 representatives of snake ancestors amid either tortoises 

 or crocodiles, but in the very extensive order of lizards 

 we might hope to find such, and indeed various kinds 

 of lizards do seem to show some special resemblance 

 to snakes, although they are probably but superficial 

 ones. 



The most obvious distinction between snakes and 

 almost all lizards, is that the latter have two pairs of 

 limbs, while the former have not one. But among the 

 lizards known as seines (whereof one was a favourite 

 ingredient in the medicines of former days), the limbs, 

 as we go through a long series of forms, become smaller 

 and smaller, till they become as minute proportionally as 

 are those of the batrachian amphiunia.* Some of these 

 lizards have a single pair of limbs, the hinder ones, while 

 the body is extremely elongated. Certain Australian 

 lizards (Delma) have no fore limbs, Avhile the hind limbs 

 are only represented by a minute pair of flattened lobes, 



* See ante, p. 10). 



K 



