RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 263 



to spend a few days on the work. The study of the collections is still 

 incomplete, and considerable field-work remains to be done before any 

 satisfactory correlation can be made, but the preliminary results seem 

 to indicate a correlation with the formations in Kentucky rather than 

 with those in New York. The important fact, mentioned before, of 

 the identification of the fauna of the Leray-Black River in the strata 

 just above the pure quarry rock gives a datum plane for correlation. 

 Above this zone, but still in the strata called " Black River" by Collie, 

 is found the fauna with Echinosphaerites, and in the lowest " Trenton" 

 (A 8 of Collie), one finds fossils such as Cryptolithiis tessellafus, Orthis 

 tricenaria, Dinorthis, and others which suggest the Hermitage of 

 Kentucky. The "Trenton" has a thickness of 600 feet, and at the 

 top, Cryptolithus comes in a. second time, as in the Cynthiana of 

 Kentucky. In our present state of knowledge, it must be confessed 

 that the thickness of the section, the general likeness of the faunas, 

 and the two occurrences of Cryptolithus,' are the principal bases on 

 which the correlation is made. So far the upper Echinosphaerites 

 zone with Christiania has not been found at Bellefonte, but the general 

 similarities of the sections at Chambersburg and Bellefonte are such 

 that we fully expect work in the intervening areas to establish a fairly 

 secure correlation between them. 



GENERAL DISCUSSION OF RUSSIAN EARLY ORDOVICIAN 



FAUNAS. 



The correlations attempted above have been based largely upon 

 stratigraphic position and "guide fossils." It remains to compare 

 in a little more detail the faunas of the strata which have been corre- 

 lated. 



Walchow and Kunda formations. 



The part of the correlation which I must most justify to American 

 students is, probably, that in which I agree with most Continental 

 authors, in assigning the Walchow and Kunda formations, Bu and 

 B,,i, to the horizon of the American Beekmantown. Therefore, I 

 wish, in addition to what has already been brought out, to discuss the 

 faunas of these two formations in some detail. Bassler has correlated 

 the two formations, in a general wav, with the lower part of the Black 



