462 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 21, 



sions may be seen in situ on much disturbed surfaces ; but they are 

 sohtary and do not add to the evidence. 



Conclusion. — These are the data by which I have been conducted 

 to the important conclusions which I venture to embody in this 

 communication . 



The same strata, however, vdll no doubt reveal additional evidence 

 when those parts shall be exposed which are now concealed by de- 

 tritus. But although fresh facts may throw new light on the natural 

 affinities of the creatures that produced these interesting phaenomena, 

 and may even multiply their genera and species, little can be wanting 

 to prove that the tridactyle impressions and casts of impressions in 

 the Wealden were produced by the feet of animals, and that those 

 animals were bipeds. 



The sum of the preceding facts, and the inferences that seem to 

 result from them, are as follow : — 



1st. That, from the number and arrangement of certain large 

 trifidal bodies occurring in the Wealden formation, and from their 

 general uniformity of character, position, and direction, bipedal 

 animals having tridactyle feet of enormous proportions lived during 

 the Wealden epoch*. 



2ndly. That the alternation of right and left footsteps proves the 

 animals to have been biped. 



Srdly. The numbers and position of the toes seem to ally these 

 animals to birds ; — while, however, it may be regarded as undeter- 

 mined whether these gigantic creatures were birds, or reptiles with 

 ornithic characters. 



It is necessary to remark that the striking evidence afforded by the 

 continuous lines of tracks is not impaired by the want of continuity 

 in the single tracks ; which is partly occasioned by the laminations 

 of the rocks, and the distribution of the tracks over the different 

 layers. The tracks b b and dd, in Plate XIX. fig. 1, for example, 

 are suddenly terminated by the lines 1 1 and in m, which represent 



* That a uniserial or quasi-bipedal track may be produced by a quadrupedal 

 auimal, we have strong evidence afforded by the recent uniserial tiidactylous 

 footprints found by Mr. E. Hopkins on the sand and mud-banks of the Magda- 

 lena River in South America, briefly noticed in Report Brit. Assoc. 1845, Traus. 

 Sect. p. 52. These prints Mr. Hopkins, after careful investigation, discovered to 

 have been made by a pachydermatous quadruped, the " Dante " or Tapir. The 

 impressions are all trifid and pachydactylous ; some of them 14 inches long, and 

 4 feet asunder ; others 6 inches long, and 22 inches apart ; and they occur in 

 single rows, with the toes of the footsteps pointed outwardly and alternately to 

 right and left. Interspersed amongst these peculiar footprints were the ordinary 

 tracks of birds and tortoises. 



In a note with which Mr. Hopkins has favoured me, he observes, " It was diffi- 

 cult at first to conceive how a quadruped could produce such angular steps ; but, 

 on minutely examining the impressions on the mud-banks, we detected a double 

 marking in each print. Some of these animals are as large as mules ; and I saw 

 many of them afterwai'ds, and watched the variable impression they made when 

 walking on sand-banks, mud-banks, up-hill, and down-hill. The double impres- 

 sion could not be detected on the sand-banks ; it was only on the mud that we 

 could detect that the Dante in walking places the hind-foot in the exact place 

 occupied alternately by the fore-foot." — [August 2 4, 1854.] 



