OF FOSSIL FOOTMARKS. 263 



of the mud. The sti'iking resemblance between the mud thus 

 impressed, and the surface of the sandstone showing rain drops, 

 renders it quite probable that the latter were produced in a man- 

 ner similar to the former. I would, also, refer to a common brick 

 kiln, for an illustration of this subject. After the bricks are moulded, 

 rain sometimes falls upon them before they are burnt ; in which 

 case, after burning, their surface appears like the fossil rain drops 

 almost precisely. I have noticed, likewise, upon burnt bricks, 

 impressions of the human foot, or hand, made before burning, 

 which were as perfect as the fossil footmarks. Such facts help 

 to remove our difficulties as to the manner in which the impres- 

 sions of rain drops and footmarks might have been preserved. 



Half a mile west of the prolific locality of footmarks in the 

 southeast part of Northampton, and at an elevation of more than 

 one hundred feet above Connecticut river, I noticed several 

 specimens of O. elegans, on the red micaceous sandstone : and 

 should a quarry be opened there, it could hardly fail to furnish 

 specimens equal to those from Wethersfield. 



I lately succeeded in uncovering a surface of gray fine mica- 

 ceous sandstone, at the locality first named above, on which were 

 exhibited seven continuous tracks of the Ornithoidichnites gigan- 

 teus. The right and left foot are shown most strikingly ; and it 

 is hardly possible for the beholder to doubt that they were produ- 

 ced by a biped animal walking over the surface with strides from 

 three to four feet long. I was able to raise a slab, fourteen feet 

 long, containing four of these tracks, and had it conveyed to the 

 Cabinet of Amherst College ; where it forms the most sti'iking 

 specimen of footmarks in my possession. I hope soon to add the 

 other three ; so that the whole seven shall again be exhibited in 

 the same position as in the quany. 



Dr. S. L. Dana has recently presented me with some deposits 

 of copper, prepared by h^m in electi'otype processes, which beau- 

 tifully illustrate the manner in which the mud, on which animals 

 had trod, retained the impressions of the tracks through several 

 successive layers upwards. Even the finest marks upon the 

 original, of which a copy is to be taken, are exhibited through a 

 considerable thickness of the deposited copper, as an examination 



