438 NEW YORK STATE MUSEUM 



distinct in their composition, it is believed that exact correla- 

 tions will be possible even with regions so remote as the sec- 

 tions in Scandinavia, on the continent of Europe and in Aus- 

 tralia, for these organisms seem to have maintained to a degree 

 not displayed by others their value as time -markers in the suc- 

 cession of the early Siluric rocks. 



1 The lowest horizon is characterized by innumerable ex- 

 amples of Didymograptus, specially D. n i t i d u s and D. 

 pa t ul u s . 



2 The next fossil-bearing beds are the richest in species, and 

 the state of preservation is the most excellent. They contain 

 a Tetragraptus and Dichograptus fauna, nearly all the species 

 of these genera, which were described by Hall from the Quebec 

 beds, and several additional ones being present. The fauna of 

 these two horizons combined is that reported from the " main 

 Point Levis zone " of Hall. This has been referred to the lower 

 Calciferous or Beekmantown formation. 



3 Farther up the creek is another series of graptolite bed» 

 characterized by Didymograptus bifidus and P h y 1- 

 lograptus anna, these two species comprising the ma- 

 jority of all specimens. Neither of them occurs in the first two 

 horizons, but they are characteristic forms of the Phyllo- 

 graptus anna zone of St Anne river, Quebec. 



4 Next follows the great mass of the quarry beds consisting 

 of heavy banks of greenish grits with thin shaly partings, the 

 latter carrying innumerable specimens of Phyllograptu» 

 typus, P. anna and P. angustifolius. Besides these 

 Didymograptus bifidus, D. similis, Thamno- 

 graptus anna and others. They probably represent the 

 upper part of the Phyllograptus anna zone. 



5 About 800 feet farther up the creek are two narrow black 

 bands intercalated in the dark gree^nish gray, barren shales, 

 which carry a very luxuriant assemblage of fossils, having not 

 less than 18 species, all of which are new to the New York 

 faunas. Two of these are brachiopods, viz: L i n g u 1 a q u e - 

 b e c e n 8 i 8 and a large oboloid representing a new generic 



