102 
EXTINCT MONSTERS. 
at South Kensington, and also some of the gigantic tracks already 
alluded to. (Gallery IV. on plan, Wall-cases 5 and 6 ; and 
Gallery XL, Wall-case 7.) 
The Bernissart specimens even afford some evidence as to 
the nature of the integument, or skin, and this supports the 
idea previously held that the creature possessed a smooth skin, 
or, at least, only slightly roughened. The muzzle was quite tooth- 
less, and perhaps may have been sheathed in horn, like the beak 
of turtles — an arrangement highly useful for biting off the leaves of 
trees. 
Fig. 23. — Tracks of Iguanodon^ much reduced. (From Wealden strata, 
Sussex.) 
Probably it passed much of its time in the water, using its 
immense powerful tail as an organ of propulsion. When 
swimming slowly it may have used both sets of limbs, but when 
going fast it probably fixed its fore limbs closely beside its body, 
and drove itself through the water by means of the long hind 
limbs alone. Mr. Dollo, of Brussels, is preparing a final mono- 
graph on the Bernissart Iguanodons, a work to which palaeontolo- 
gists eagerly look forward. There cannot be much doubt that 
