9& ANIMAL LIFE PAST AND PRESENT. 



Turning from these latest modifications into which 

 the Long-Necked Lizards were finally developed, and 

 looking back at the earliest known representatives of 

 the group, we find in the strata lying below the Lias, 

 and thus forming the very base of the Secondary rock- 

 series, the remains of a number of more or less closely 

 allied forms, the largest of which did not exceed a 

 yard in length. These small reptiles were evidently 

 ancestral types of the larger species found in the Lias, 

 but they exhibit certain structural features clearly 

 indicating that they were in great part of terrestrial 

 or fresh-water habits, and their whole organisation 

 departs less widely from the general reptilian type 

 than is the case with their successors in time. Thus 

 we reach the conclusion that the Long-Necked Lizards, 

 like the Fish-Lizards, were in all probability descended 

 from small land reptiles, and have been gradually 

 more and more modified for the exigencies of a purely 

 marine life. In this respect, therefore, these ancient 

 creatures present a precise analogy to the Whales and 

 Porpoises of to-day. 



