GEOLOGY. 293 



twenty teeth of probably three or four genera of saurians, all con- 

 verted into dolomite, occur on a piece of sandstone six by three 

 inches. It is a singular fact that while the teeth are dolomitic casts 

 only, the bones in the same stone remain unchanged, retaining their 

 original structure. 



Associated with the above fossils in the sandstone are numerous 

 plant remains, mostly of a broad sulcated stem without joints or 

 branches ; as far as noticed they retain the same width their entire 

 length, and are from one-half to two inches broad, and from six to 

 eight inches long. 



"The shales, sandstones, and fossils of the Phoenixville tunnel bear 

 a remarkable resemblance to those of Nagpur and Mangali, Central 

 India, described by Messrs. Hislop and Hunter, Journal Geological 

 Society, London, vols. x. and xi., and referred by them to the lower 

 Jurassic age. 



RELATION OF THE DILUVIAN OR QUATERNIAN PERIOD TO 

 THE PRESENT OR MODERN EPOCH. 



Although in all treatises on geology the Diluvian and the present 

 or modern epoch are considered as distinct, it has nevertheless always 

 been extremely difficult to fix the precise limit of demarcation be* 

 tween them. In the following article, translated for Siliiman's Jour- 

 nal from the Bibliotheque Universelle de Geneve, the celebrated ge- 

 ologist and palaeontologist, M. Pictet, seeks to demonstrate that the 

 Diluvian and modern epochs are really one, and that they ought to 

 be so considered, and designated by a common name. For this pur- 

 pose, he says, I shall first demonstrate that all actual and modern 

 faunas have existed from the origin of the Diluvian period. I shall 

 next inquire what differences exist between the Diluvian fauna and 

 the present fauna, and shall show that they consist only in the disap- 

 pearance of a limited number of the larger species. For this purpose 

 I have arranged a complete catalogue of the fauna of European mam- 

 mifers, and Iliave inquired which have not been found in the fossil 

 state, and what are those the bones of which have been found buried 

 in the Diluvian beds, with the fossil elephant or with the cavern 

 bear. Reasoning upon comparable and sufficiently certain facts, I 

 have excluded from this list, 



1st. Marine mammifers, in view of the difficulty of determining the 

 age of marine Quaternian deposits. 



2d. Mammifers of remote regions, whose bones are not likely to be 

 found in the more explored and better known Diluvian deposits of 

 Central Europe. Thus, I have not considered as important either 

 the monkey of Gibraltar, or the small species on the confines of 

 Asiatic Russia, or those which have been recently discovered in 

 Sicily or in Turkey. I have confined myself to those actually living 

 in places where the Quaternian deposits are well known. Besides 

 this, the excellent work of Eichwald proves the existence of the 

 same state of things in Russia as in England, Belgium, France, Ger- 

 niauy, or Switzerland. 



The following are the principal facts obtained from an analysis of 

 my catalogue, viz. : 



25* 



