206 NEW YORK STATE MUSEUM 



not been established. When complete, the stem of the genotype T. typus 

 is surrounded by an inextricable mass of tufts of such finer branches. 



No indications of a more complex composition of the branches of dif- 

 ferent types of thecae, such as found in Dendrograptus, have been noticed. 

 But even if these apparently simple thecae are indeed of more complicate 

 structure, the species is still so distinctly different in its general mode of 

 growth and the form of the thecae from Dendograptus s. sir. that it repre- 

 sents a good genus. It is by the same characters equally well separated 

 from Mastigograptus. 



Nemagrapsus capillar is Emmons is but a drifted and mace- 

 rated distal portion of a T . t y p u s, but being described and named before 

 the other parts, the name has precedence over the others. 



The genus as now known would comprise : 

 T. capillaris Emmons ( + T. typus + T. barrandii) T. affinis ]Vhiteaves 

 T. scoticus Lafiworth T. anna Hall 



The latter species is from the Point Levis shales of Quebec. Perhaps 

 also P t i 1 o g r ap t u s tenuissimus Rued, from the uppermost zone 

 of the Deepkill shales would be more properly referred to this genus than 

 to Ptilograptus, but both T. anna and Ptilogr. tenuissimus can 

 not be safely placed here before their distal mode of branching and their 

 thecal structure are known. Also of T . scoticus and T . affinis 

 only the stipes with the bases of the main branches of the first order are 

 known. 



Thamnograptus capillaris (Emmons) 



Plate 10, figures 4-8; plate 12, figures 9-16 



Nemagrapsus capillaris Emmons. Amer. Geol. i S55. v. 1, pt II, p. 109 ; pi. i, 



fig. 6 

 T h a m nograptus t y p u s Hall. Pal. N. Y. 1S59. 3:519, fig- i> 2 

 'I' h a m nograptus c a p i 1 1 a r i s Hall. Ibid. p. 5 20, fig. 3 

 Rast rites barrandi Hall. Ibid. p. 521, 522, fig. 1,2 

 T h a 111 n g r a p t u s capillaris, T . typus, Rastrites b arr a n d i Walcott 



Geol. Soc. Am, Bui. 1890. i : 338 

 Thamnograptus capillaris, T. typus, Rastrites barrandi Walcott. 



Alb. Inst. Trans, v. 10. 1883. (Advance sheets 1X79. 11.35) 



