FOSSIL FOOTSTEPS. 
215 
instead of legs, had four large paddles, resembling those of 
the Plesiosaurus and the Whale : one great use of these 
was probably to assist in raising the animal to the surface, 
in order to breathe, as it apparently had not the horizontal 
tail, by means of which the Cetacea ascend for this purpose. 
All these characters unite to show that the Mosasaurus 
was adapted to live entirely in the water; and that 
although it was of such vast proportions compared with 
the living genera of these families, it formed a link 
intermediate between the Monitors and the Iguanas. How¬ 
ever strange it may appear to find its dimensions so much 
exceeding those of any existing Lizards, or to find marine 
genera in the order of Saurians, in which there exists at 
this time no species capable of living in the sea, it is 
scarcely less strange than the analogous deviations in the 
Megalosaurus and Iguanodon, which afford examples of 
still greater expansion of the type of the Monitor and 
Iguana, into colossal forms adapted to move upon the land. 
1 hroughout all these variations of proportion, we trace the 
persistence of the same laws, which regulate the formation 
of living genera ; and from the combinations of perfect 
mechanism that have, in all times, resulted from their opera¬ 
tion, we infer the perfection of the wisdom by which all 
this mechanism was designed, and the immensity of the 
power by which it has ever been upheld.” 1 
One more extract shall be given, a brief but eloquent 
passage on Fossil Footsteps—the marks of reptiles of 
whose bones no remains have been found. 
“ The Historian or the Antiquary may have traversed 
the fields of ancient or of modern battles ; and may have 
pursued the line of march of triumphant conquerors, whose 
armies trampled down the most mighty kingdoms of the 
world. The winds and storms have utterly obliterated the 
ephemeral impressions of their course. Not a track remains 
of a single foot, or a single hoof, of all the countless millions 
1 Bridgewater, vol. i., chap. xiv. 
