Cn. XXII] VALLEY OF THE CONNECTICUT. 349 



relation in its osteology both to clielonians and birds. Other imprints, 

 again, are like those of turtles. 



Mr. Darwin, in his " Journal of a Voyage in the Beagle," informs us 

 that the " South American ostriches, although they live on vegetable 

 matter, such as roots and grass, are repeatedly seen at Bahia Blanca (lat. 

 39° S.), on the coast of Buenos Ayres, coming down at low water to 

 the extensive mud-banks which are then dry, for the sake, as the Gauchos 

 say, of feeding on small fish." They readily take to the w^ater, and 

 have been seen at the bay of San Bias, and at Port Valdez, in Patago- 

 nia, swimming from island to island. ''^' It is therefore evident, that in 

 our times a South American mud-bank might be trodden simultaneously 

 by ostriches, alHgators, tortoises, and frogs ; and the impressions left, in 

 the nineteenth century, by the feet of these various tribes of animals, 

 would not differ from each other more entirely than do those attributed 

 to birds, saurians, chelonians, and batrachians, in the rocks of the Con- 

 necticut. 



To determine the exact age of the red sandstone and shale containing 

 these ancient footprints in the United States, is not possible at present. 

 No fossil shells have yet been found in the deposit, nor plants in a de- 

 terminable state. The fossil fish are numerous and very perfect ; but 

 they are of a peculiar type, which was originally referred to the genus 

 Palceoniscus, but has since, with propriety, been ascribed, by Sir Philip 

 Egerton, to a new^ genus. To this he has given the name of Ischyj^terus, 

 from the great size and strength of the fulcral rays of the dorsal fin 

 (from <V%ug', strength, and itrspov, a fin). They differ from Palceoniscus, 

 as Mr. Redfield first pointed out, by having the vertebral column pro- 

 longed to a more limited extent into the upper lobe of the tail, or, in 

 the language of M. Agassiz, they are less heterocercal. The teeth also, 

 according to Sir P. EgertoUj who, in 1844, examined for me a fine series 

 of specimens which I procured at Durham, Connecticut, differ from those 

 of Palceoniscus in being strong and conical. 



That the sandstones containing these fish are of older date than the 

 strata containing coal, before described (p. 330) as occurring near Rich- 

 mond in Virginia, is highly probable. These were shown to be as old 

 at least as the oolite and lias. The higher antiquity of the Connecticut 

 beds cannot be proved by direct superposition, but may be presumed 

 from the general structure of the country. That structure proves them 

 to be newer than the movements to which the Appalachian or Alleghany 

 chain owes its flexures, and this chain includes the ancient coal forma- 

 tion among its contorted rocks. The unconformable position of this JVew 

 Red with ornithicnites on the edges of the inclined primary or paleozoic 

 rocks of the Appalachians is seen at 4 of the section, fig. 505, p. 388. 

 The absence of fish with decidedly heterocercal tails may afford an 

 argument against the Permian age of the formation ; and the opinion 

 that the red sandstone is triassic, seems, on the whole, the best that we 

 can embrace in the present state of our knowledge, 



* Journal of Voyage of Beagle, <fec. 2d edition, p. 89, 1845. 



