58 EXAMPLES OF CONNECTION BETWEEN ORDERS. 



possession of all the forms which it contains, would present links 

 of transition such as these, towards the groups which surround it. 

 But, for the reasons already stated (27-30), they are frequently 

 wanting, although they are continually being brought to light by 

 the rapid extension of Zoological research. A few examples of 

 this kind may be here adverted to. It has been already stated, 

 that the different families and genera of the order Pachydermata, 

 widely as they appear to be separated when we look at the exist- 

 ing species alone, are in reality connected most closely by fossil 

 species, which present the most remarkable and interesting com- 

 binations of characters, that are now found separately in the 

 forms with which we are familiar. The chief of these will be 

 pointed out in their proper place. The dif- 

 ferent orders of Reptiles, although very dis- 

 tinct as regards their types, viz. Turtles, 

 Lizards, Serpents, and Frogs, are yet most 

 closely connected together by links of tran- 

 sition, that pass between the typical forms. 

 Thus, between the Turtles (Fig. 13), and 

 the Lizards (Fig. 14), the passage is esta- 

 blished by species of Turtles, which have a 

 long neck, tail, and legs, and a small shell, 

 which only covers a part of the back, (known 

 F/O. ^-TORTOISE. ag Alligator Tortoises,) and species of 

 Lizards, that have a very firm covering of large scales or plates 



FJG. 14, CROCODILE. 



on the back, which reminds us of the shell of the Turtle. 

 Again, from the true or typical Lizards, which have four legs, 

 we pass to the Serpents (Fig. 15), which have none, by means 

 of such species of Lizards as the one represented in Fig. 16, 

 which have the body and tail very much prolonged, and the 



