GRAPTOLITES OF NEW YORK, PART 1 579 



The habits of the forms of the genus indicate more than those of any 

 others a sessile mode of life, for the stout trunk and the irregular 

 ramifications remind so strongly of the structure of recent sessile hydrozoans 

 that this similarity has frequently been cited as suggestive of a like mode 

 of life of at least these forms. Moreover, there have been observed basal 

 expansions of the stem, assuming the form of irregular bulbs or disks, 

 which also would be most readily explained as organs of attachment. It 

 is however to be remembered that no cases of actual attachment and fixa- 

 tion have yet been recorded, and that, at the Deep kill at least, and also 

 in the Quebec shale and apparently in Wales, the species of Dendrograptus 

 occur in the same facies and associated with all the other graptolites, as 

 Dictyonema, Diplograptus, Climacograptus. 



Dendrograptus flexuosus Hall 



Plate 4, figure 5, 6, 8-10 



Dendrograptus flexuosus Hall. Canadian Organic Remains, decade 2. 1865. 



p.l27f, pl.17, fig.l, 2 

 Dendrograptus flexuosus Hopkinson & Lapworth. Quar. Jour. Geol. Soc. 



1875. 31:662f, pl.36, fig.3a-3d 

 Dendrograptus flexuosus Roemer & Freeh. Lethaea palaeozoica, Bdl. 1897. 



p.578 

 Dendrograptus cf. gracilis Ruederaann. N. Y. State Paleontol. An. Rep't 



1902. p.555 



Description. Rhabdosome broadly flabellate (or infundibuliform ?), 

 attaining a length of an inch or more. Branches radiating from a short, 

 stout nemacaulus, slender, flexuous, bifurcating frequently and somewhat 

 regularly, diverging at first under a considerable angle, but soon becoming 

 subparallel, the distal ones somewhat undulating. Thecae numbering 6-14 

 in 10mm; long, narrow, projecting distinctly, inclined at an angle of about 

 20° ; apertural margin forming an angle of 80° with the axis of the branch. 



Position and localities. Common in graptolite bed 2 (Tetragraptus 

 zone) and rarer in graptolite bed 3 (zone with Didymograptus 

 1) i f i d u s ) at the Deep kill. 



