782 NEW YORK STATE MUSEUM 



PLATE 17 



Genus trigonograptus Nicholson 

 Trigonograptus ensiformis Hall (sp.) 



Page 727 



1 Very young rhabdosome 



2 A more advanced growth stage 



Ash hill quarry, Mt Moreno, Columbia co. N. Y. 



3 Largest specimen observed 



4, 5 Fragments of rhabdosomes showing the thecal walls 



6 Rhabdosome which shows the thecal apertures 



7 Fragment of another rhabdosome which shows the thecal apertures 



8 Nearly complete rhabdosome in which the process of the sicular end is 



■retained 



9 Rhabdosome in which the direction of the apertural margins in relation to 



the axis of the thecae is shown. x2 

 Graptolite bed 7 of the Deep kill section 



Genus diplograptus McCoy 



See pi. 16 



Diplograptus dentatus Brongniart (sp.) 



Page 719 



10, 11 Rhabdosomes of typical appearance and dimensions 



Ash hill quarry, Mt Moreno, Columbia co. N. Y. 

 12 Frontal aspect of a rhabdosome 



Graptolite bed 7 of the Deep kill section 

 18 A young rhabdosome retaining the long sicular spine 



Ash hill quarry, Mt Moreno, Columbia co. N. Y. 



Genus caryocaris Salter 

 Caryocaris cf. oblongus Gurley 



Page 738 



14-16 Three of the most common aspects of the organism 



Lower Cham plainic beds at the Mettanee river, east of North 

 Granville, Washington co. N. Y. 



