IMPRESSIONS ‘OF THE PAST 43 
hand that Dr. Kaup christened the beast sup- 
_ posed to have made them Cheirotherium, beast 
with a hand, suggesting that they had been 
made by some gigantic opossum. As the 
tracks measure five by eight inches, it would 
have been rather a large specimen, but the 
mammals had not then arisen, and it is gener- 
ally believed that the impressions were made 
by huge (for their kind) salamander-like creat- 
ures, known as labyrinthodonts, whose _re- 
mains are found in the same strata. 
Footprints may aid greatly in determining 
the attitude assumed by extinct animals, and 
in this way they have been of great service in 
furnishing proof that many of the Dinosaurs 
walked erect. The impressions on the sands 
of the old Connecticut estuary may be said to 
show this very plainly, but in England and 
Belgium is evidence still more conclusive, in 
the shape of tracks ascribed to the Iguanodon. 
These were made on soft soil into which the 
feet sank much more deeply than in the Con- 
necticut sands, and the casts made in the nat- 
ural moulds show the impression of toes very 
clearly. If the animals had walked flat-footed, 
