GEOLOGY. 375 



the determination of the exact age of this sandstone, the only rock in this 

 country east of the Mississippi, occurring between -the Carboniferous and the 

 Cretaceous, we cannot be too cautious in the use of evidence. One or two 

 considerations are, therefore, here suggested. In the first place, the Fauna 

 and Flora of America, of this modern epoch, is represented in Europe, and 

 quite strikingly, as has been shown by the Fauna and Flora of the later 

 tertiary of Europe. The life of corresponding ages in the two continents lias 

 thus been older in America than in Europe. This is one point to be well 

 weighed. Again, in determining the age of a rock from its fossils, we should 

 rather look to those which indicate the more recent period, than those which 

 bear the other way. This criterion would bring us right with regard to our 

 own epoch, while, by avoiding it, we might be able to prove that we in 

 America arc of the Tertiary age of the world. Now, as Mr. Red field has 

 shown, the fossil fishes, the most characteristic species of any formation, 

 are but half heterocercal and come nearer to the Jurassic type than the Tri- 

 assic. There is hence reason for the opinion, notwithstanding the important 

 evidence brought forward by Dr. Emmons, that the Lias period may be 

 represented by the formation ; and we may be nearest the truth if we regard 

 the whole formation as corresponding to the Lias and the latter half of the 

 Trias. The examinations bv Mr. Heer accord with this conclusion. The 



tt 



European subdivisions of the Trias we should not look for on this continent, 

 even if we had the whole of the formation, any more than the European 

 subdivisions of the Devonian in the American Devonian. American geology 

 is deeply interested in the decision of this question, and owes much to Pro- 

 fessor Emmons for all that he has done towards its elucidation. 



FOSSILS OF THE CONNECTICUT RIVER SANDSTONES. 



At a recent meeting of the Boston Society of Natural History, President 

 Hitchcock exhibited specimens of impressions, which he supposed to be those 

 of a Myriapod, found at Turner's Falls on Connecticut River. 



He also presented specimens of depressions found in the same series of 

 rocks, of regular polygonal forms, generally from five to eight sided, shal- 

 low and about an inch in diameter. Similar depressions have been found 

 in the Niagara limestone of New York, of two or three feet in diameter. 

 These last have been referred to the action of tadpoles, and President Hitch- 

 cock was also inclined to refer the specimens from Connecticut River to the 

 same cause. 



Mr. II. further stated that he was now doubtful if the tracks which he had 

 supposed to have been made by birds, in the Connecticut Valley sandstone, 

 were really produced by birds, since one great argument, namely, that of the 

 number of phalanges in the toe, is lost. Tracks of an animal which was cer- 

 tainly a quadruped, are now found, presenting the same number of phalanges 

 and toes as the dinornis. 



At the Montreal meeting of the American Association, Dr. Hitchcock 

 also read a paper on the age of the Connecticut River sandstones, and de- 

 duced the following conclusions : 



1. There is a belt of sandstone lying in Massachusetts, immediately above 



