_ Notice of a small Ornithichnite. 215 
A lacustrine origin is out of the question, because such an uni- 
versal diffusion of land shells with no fresh-water shells among 
them, except Cyclas and small Paludine, could under no cir- 
cumstances take place in a lake of considerable size. In that 
case, Unios and large fresh-water shells would be the predominant 
fossils, and land shells of rare occurrence. Admitting the loam to 
have been deposited by the overflows of the ancient Mississippi, 
it assumes a‘feature of extraordinary interest in proving a con- 
siderable elevation of the Eocene strata in a period as recent as 
that when the mastodon existed. This rise of land, I have no 
doubt, was coeval with that of the Gnathodon beds of Florida, 
Alabama, and Louisiana, of the keys of Florida, and of the oyster 
shell deposits of Virginia, Maryland, and New Jersey. At this 
_time the change of climate occurred which has restricted the liv- 
ing Gnathodon to the estuaries of the Gulf of Mexico, and which 
was probably connected with the disturbance or revolution that 
exterminated the mastodon and its gigantic associates. 
— 
Arr. XX.—Notice of a small Ornithichnite; by C. B. Avams, 
State Geologist of Vermont, &c. 
Tur specimen from which the following figures were drawn, 
was obtained in Wethersfield, Ct., at the locality of Ornithich- 
nites described in the Final Report on the Geology of. Map 
1g. . 
setts, pp. 466-7, and with many others from 
the same locality, is now in the cabinet of Mid- 
dlebury College, Vermont. It is a fine red 
slate of the new red sandstone. The tracks 
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have had slender toes, but a broad heel, like ae 
Polemarchus gigas, Hitehk.,¢ which, as in that 
“ase, indicates a much heavier animal than would have been sup- 
z Posed from the slenderness of the toes. 'These two animals, so 
+ Proceedings of Sixth Meeting of Association of American Geologists, p. 24. 
