1854.] BECKLES WEALDEN FOOT-TRACKS. 463 



the edges of the layers, while the track a a, which runs in the direc- 

 tion of these lines, and remains on the same layer, is continued over 

 the whole of the exposed surface. 



Some impressions, moreover, even on the same laminae, are such 

 obscure memorials of the originals, that it is easy to infer that tidal 

 erosion may have obliterated others, by which these were probably 

 prolonged into tracks ; a deduction warranted also by the condition 

 of some entire lines, which, although well defined, contain some 

 marks less vividly expressed than others, but which will probably 

 disappear, and leave those that are more forcibly developed as the 

 solitary representatives of a former track. 



Impressions of the phalanges and integuments might have proved 

 incontestably that these trifids were organic, or have led to the de- 

 termination of the class of animals that produced them ; but how far 

 the absence of these anatomical details affects the evidence before us, 

 may be inferred from the fact that all the resources of argument 

 were exhausted before the persevering investigators of the footprints 

 of the New red sandstone of Connecticut obtained that structural 

 proof which the scepticism of many men of science rendered ne- 

 cessary. 



The occurrence of the footprints along what was no doubt the 

 muddy shores of the estuary in which the Wealden was deposited, 

 points out a habit that rendered a great expanse of foot indispensable 

 to an animal of such implied massiveness of structure. 



The natural casts in my collection present at least six varieties in 

 size, and I have had the gratification to see in situ tracks of im- 

 pressions corresponding to each of these casts except one. 



I have not observed an indication of a hind-toe to any of the foot- 

 prints that occur to the west of Hastings*. 



The magnitude of the footprints harmonizes well with the osteo- 

 logy of the Wealden. Our experience of the colossal Ornithoid- 

 ichnites of the Connecticut Valley prepared us for what might prove 

 almost incredible developments of organic life ; and, if there was a 

 period in geological history, antecedent to the appearance of mam- 

 malia, when we might have expected such phsenomena, it was the 

 sera that ushered in those stupendous saurians which were probably 

 contemporaneous with the gigantic authors of these interesting 

 relics. 



Lastly, I would remark, that in using the word OrnithoidicJmites, 

 1 intend rather to convey an intimation that the trifidal bodies are of 

 organic origin, than to determine the affinities of the animals that 

 produced them : I adopt the term, therefore, provisionally and most 

 cautiously. Although the evidence seems to connect the footprints 

 with the class Aves, yet I am not aware that it is such as positively to 

 exclude animals of a different organization. Descriptions having for 

 their object the establishment of the class of the animals might be 

 premature and fruitless in the present state of the evidence, and only 

 hamper an attempt which is simply intended to prove their existence. 



* See Quart. Journ. Geol. Soc. vol. viii. p. 396. figs. 1 & 2. 



