Prof. Hitchcock on Fossil Footmarks, Lincolnite, <$*c. 63 



its in relief three tracks of the huge Ornithoidichnites gigantens ; 

 the right and left feet being distinctly marked by the phalangeal 

 protuberances of the toes. Between the first and second tracks, 

 the stride is fifty-five inches; and between the second and third, 

 fifty-one inches ; which, although longer than usual, is conside- 

 rably less than I have seen at the same locality. The track, also, 

 is about nineteen inches long, and twelve inches between the 

 tips of the outer toes, and six and a half wide behind ; whereas, 

 the specimen from the same locality, figured in the American 

 Journal of Science for January, 1836, was seventeen inches long, 

 and ten inches between the tips of the toes, and four inches and 

 eight tenths wide behind. And upon the whole, I incline to be- 

 lieve that the present example was made by a larger foot than 

 the former one.* But I ought to give a caution on this subject. 

 The fact is, there is danger of overestimating the size of these 

 larger tracks; especially those that are depressions. The rock is 

 a shaly sandstone, splitting off in fine layers, especially after 

 much exposure to the air, or the floods of Connecticut River ; 

 and as the depression often extends through many layers, the 

 difficulty is, to know on which of them the animal originally 

 trod. If we get below that layer, the track will be too large ; for 

 it is easy to see, that as we descend below the surface originally 

 trod upon, the curvature of the layers will be less in depth, but 

 broader. Even the length of the track may, in this way, be 

 somewhat increased ; chiefly, however, at the heel. I have a 

 specimen from that locality, in which the toes are nearly four in- 

 ches wide; (No. 42.) Another specimen (No. 128) requires four 

 quarts of water to fill it. A drawing of such specimens would 

 have an imposing eff'ect ; but it would be very likely to prove 

 an exaggeration ; even though the exact form of every part of 

 the foot be presented. I have noticed, however, that the mud, 

 which filled the track, is usually more or less concreted, and 

 less slaty than the surface on which the track was made ; and, 

 therefore, I have thought it safer to get the dimensions from 

 a track in relief, of this description, than from a mould. Such 

 was the character of the specimen, figured in your Journal. 

 Even though I might have found tracks at the same locality 



* Not long ago I obtained from a locality in Springfield a track in relief of the 

 remarkable Sauroidichnites polemarchius, which is fifteen inches long ; one inch 

 longer than that figured in my Final Report. 



