156 AN ATTEMPT TO DESCRIBE THE ANIMALS THAT MADE 



and Cuvieri (Didionnaire Classique dPHistoire Naturelle, Plate 120), 

 which are lizards. 



In some of the quadrupeds, the heel differs in the hind and fore 

 feet ; as, for example, the Macropterna recta and divaricans (Plate 

 15, figs. 6 and 7) ; the one being long, and the other rounded. 

 The heel of the Typopus abnormis appears to come under the long 

 variety ; but it is verj anomalous (Plate 10, fig. 6) ; as also is that 

 of the unnamed track on Plate 15, fig. 2. 



The difference between the heel of the fore and hind foot is like- 

 wise well exhibited in the Anomoepus scambus, and Ancyropus 

 heteroditus, Plate 13, figs. 1-6, and Plate 15, figs. 3 and 4. This 

 character alone would form a good one for generic, as well as spe- 

 cific distinctions. 



15. Irregularities of the under side of the foot. — The depth of 

 the impression in the rock, made by the different parts of the foot, 

 show which of them projected farthest downward. In this way 

 we ascertain that usually the middle toe was rather the most prom- 

 inent on the bottom of the foot ; at least, most of the weight of 

 the animal pressed upon it ; for we find, as already stated, that as 

 we cleave off successive layers of the rock, the middle toe remains 

 longer than the others. And of the middle toe, its central parts 

 make the deepest impression ; showing that that part bent down- 

 wards most. Of the toes, the fourth, or hind one (where three are 

 directed forward), disappears first ; showing that its articulation 

 was higher up than the others. The heel vanishes next ; proving 

 that it was placed on a higher level than the body of the foot. 



One cannot inspect a series of specimens of footmarks without 

 seeing at once that a part of the animals that impressed them 

 Avere plantigrade and a part digitigrade. Of the former, all the 

 pachydactylous tracks (Brontozoum and Otozoum) are examples ; 



