RAYMOND: CORRELATION' OF THE ORDOVICIAX STRATA. 267 



Walchow where the boundary between Bm and Ci is indefinite. 

 Still it is evident that thirteen out of seventy-seven is a much smaller 

 proportion than eleven out of twenty-six. The only conclusion which 

 it is possible to draw from the above rather remarkable array of evi- 

 dence derived from the bryozoans is that both the species and genera 

 have too great a vertical range to allow their use in direct correlations. 



Cystidea. 



Lamansky lists fifteen species of cystids, belonging to six genera (if 

 Bolboporites can be called a genus), but he places no particular specific 

 names after Cheirocrinus. As a matter of fact there are a considerable 

 number of species of cystids not enumerated by Lamansky, but that 

 does not affect the present purpose. 



Of the six genera listed, three are unknown in America. Of the 

 remaining three, Glyptocystites and Bolboporites appear in the Chazy, 

 and Cheirocrinus in the Trenton. As with the Bryozoa, it must be 

 remembered that the cystidean fauna of the Beekmantown is unknown. 

 There is plenty of proof that cystideans were present, but most of our 

 Beekmantown rocks are lithologically ill adapted either for the preser- 

 vation or recovery of fossils. 



Cephalopods. 



Vaginoceras is of course the common genus in the Kunda, and that 

 genus is represented in America by a single species found in the Chazy. 

 Other genera, like Estonioceras and Planctoceras are unknown here. 



Gastropods. 



Gastropods make their first appearance in Russia in the Kunda, 

 and the variety there is small. Of the four genera, two, ^Nlaclurites and 

 Sinuites, are found in the Beekmantown, while Raphistoma appears 

 first in the Chazy and Salpingostoma in the Stones River. 



The fauna as a ichole. 



Bringing together what has been said above, it appears that out of 

 the 186 species considered, five, all Bryozoa, have been considered as 

 identical -with species found in America, and these appear in the two 

 countries in reverse order, and thus have no significance. Of the 



