J. H0PKIN80N ON BRITISH ORAPTOLITE8. 



165 



Table showing the vertical distribution of the families and genera 

 of the Graptolitidae in Britain and in America : — 



Note — In the above table T have inserted the figures showing the supposed 

 equivalency of the graptolitic rocks of Britain and America from the evidence 

 afforded by gi'aptolites and the allied genera alone. The species afford more 

 conclusive evidence of this correlation than the genera. 



The Hudson River formation (5 and 6) includes the underlying Utica slate. 



The following arrangement of the Hydrozoa is proposed by Mr, 

 T, Hincks in his "History of British Hydroid Zoophytes." 



Ord. I, Hydroida. Sub-ord. I, Athecata (Corynida?). II, 

 Thecaphora (Sertulariadse). Ill, Gymnochroa (Hydrid^e). 



Ord, II, SiPHONOPHORA (Calycophorida? and Physophoridje). 



Ord. Ill, DiscoPHORA (Luceraariadaj), 



