492 NEW YORK STATE MUSEUM 



of the Cambric, lias also been announced lately by the present writer [1903]. 

 The taxonomic position and distribution of this zone — also found in " Hudson 

 river shales " — has been discussed in detail in the paper mentioned. It will 

 therefore suffice briefly to review here the more important facts. 



a Zone with Dictyonema flabelliforme. This zone has been found by the 

 writer to be very well exposed at the falls of the Hoosic river in the village 

 of Schaghticoke, Rensselaer co. N. Y. Its fossils are finely preserved 

 in the beds exposed at Schaghticoke, and complete series of growth stages 

 of the characteristic graptolites [pl.l] were secured at this locality. Its 

 lithologic characters, which are similar to those of the Deep kill beds of 

 Beekmantown age, can also be well studied at the falls, but the adjoining 

 formations are not exposed there. The characteristic graptolites of the beds 

 are Dictyonema flabelliforme Eichwald and Staurograptus 

 dichotomus Emmons (Clonograptus proximatus Matthew), both 

 in several varieties. 



The limitation of the graptolite fauna to hardly more than two forms, 

 the first representative of the long persistent genus Dictyonema and the 

 second a pronounced synthetic form, Staurograptus, seems to be everywhere 

 characteristic of this zone ; for in Canada, where it was recognized at nearly 

 the same time by Dawson and Lapworth in the slates trending along the 

 south shore of the lower St Lawrence, these are the only graptolites cited. 

 In the St John (N. B.) basin, where the vertical range of Dictyonema has 

 been carefully studied by Matthew, these are the principal graptolites, and 

 the species of Bryograptus cited are probably all referable to one of these 

 forms [s^6p.616j. 



In Europe, the zone is considered as marking in Scandinavia, where it is 

 widely distributed, the closing stage of the Cambric. Here also Dicty- 

 onema flabelliforme is associated with a species of Clonograptus that 

 is similar to ours, and probably also with a few representatives of Bryograptus, 

 which is another synthetic genus. The Dictyonema zone has been further 

 recognized in Esthland, Oesel, Bornholm, Belgium, Wales, western England 

 and Ireland. Brogger has demonstrated that the zone is also in Great 



