762 NEW YORK STATE MUSEUM 



PLATE 8 



Genus dichograptus Salter 

 Dichograptus octobrachiatus Hall (sp.) 



Page 634 . ' 



See pi. 9 



1 Young rhabdosome 



2, 3 Rhabdosoraes retaining the central disk 



4 Mature rhabdosome 



5 Fragment with central disk, showing the growth lines of the latter 



6 Rhabdosome in hexad stage of reduction 



7 Specimen still retaining a bifurcation of the fourth order. x2 



All originals are from gi-aptolite bed 2 of the Deep kill section with 

 the exception of that of figure (i, Avhich is from graptolite bed 7. 



