204 



NEW YORK STATE MUSEUM 



He adds that "one specimen occurs in the collection from the Niagara 

 shale, Hamilton, Ontario." The latter is a beautifully preserved specimen, 

 retaining the thecal tubes in a pyritized condition. We reproduce here 

 [pi. 3] a drawing of the type from a photograph and camera enlargements 

 of parts of the Ontario specimen to show its characters in detail. The mar- 

 gins of the branches are distinctly 

 smooth, only in one place a few thecae 

 are seen [see fig. 107]. They are nar- 

 fy m ver row and so appressed to the branch 



that they hardly project. For this 

 reason we do not believe that this form 

 can be considered as congeneric with 

 I . p 1 u m u 1 o s u s and that I nocaulis 

 is the proper receptacle for it, although 



Fig. 105-7 P a 1 a e odictyotk bella (Hall & Whit- l . 1 ■ J .1 r . 1 1 i l 1 • 



field). Natural size drawing and enlargements (x 5) of Dy tlie Width OI tile DranCIieS ailCl their 

 fragments of a specimen from tb« Niagaran of Hamil- 



ton ' 0nt> composition of many fine tubular thecae 



its close relation tc that genus is indicated. We place it, for the present, 

 with Palaeodictyota. 



Palaeodictyota bella (Hall & Whitfield) mut. recta nov. 



Plate 6, figure 6 ; plate 7, figure 6 



The shale adjoining the Clinton iron ore contains rhabdosomes of a 

 form which appears to be so little different from P . bella — at least with 

 the incomplete material at present available of both forms — that we pre- 

 fer to designate it as but mutationally different from the Rochester shale 

 type of P. bella. Its dimensions, notably the thickness of the branches 

 are the same as in P. bella, but its habitus is a little more erect or less 

 scraggy, owing to slightly smaller angles of divergence of the bifurcating 

 branches and somewhat greater intervals of bifurcation. 



THAJHNOORAPTUS 1 [all 



The genus Thamnograpius, erected in [859 [Pal. X. Y. v. 3 | by 11. ill 

 for two forms of the Normanskill shale, has ever since remained anions' - 



