590 NEW YORK STATE MUSEUM 



Ptilograptus geinitzianus Hall 



Plate i, figure 16 



Ptilograptus geinitzianus Hall. Canadian Organic Remains, decade 2, 



1865. p.l40, pl.21, fig.5-8 

 Ptilograptus geinitzianus Gurley. Jour. Geol. 1896. 4:300 

 Ptilograptus geinitzianus F. Roemer & Freeh. Lethaea palaeozoica, Bdl. 

 1897. p.580 



Description. This species is represented by a few somewhat frag- 

 mentary specimens which consist of a branch and the bases of the 

 branchlets. One branch, which has a length of 21 mm, is broad (about .8 mm 

 wide), little tapering and consisting of a thick chitinous test. The branch- 

 lets are closely alternating on opposite sides of the branch (those of the 

 same side are 1 . 5 mm apart), diverge from the branch at an angle of about 

 50° and have a basal width of . 5 mm. They are appressed to the stem 

 for a short distance. No traces of thecal apertures are observable on 

 them; the only indication of such an aperture being visible on the stem, 

 near the base of a branch. 



Position and localities. The specimens were found at the Deep kill in 

 graptolite bed 3, the lowest bed of the zone with Didymograptus 

 bif idu s . 



Hall records it as occurring in the Quebec shales at Point Levis with- 

 out mentioning its associates, but Grurley observed it in the Main Point 

 Levis zone. It seems, hence, at the Deep kill to pass beyond its range in 

 the Quebec region. 



Memarlcs. Hall's more complete specimens, which were obtained in 

 the Quebec shale of Point Levis, show that the rhabdosome is irregularly 

 branching. This species is said to differ from P . p 1 u m o s u s by its 

 stronger and coarser habit, its more frequent and irregular branching, its 

 broad, flattened branches and the broader branchlets. It is doubtful 

 whether the thecal apertures are as regularly distributed on one face of 

 the branchlets as represented in the original drawings of the species. 



