GRAPTOLITES OF NEW YORK, PART 2 317 



distinguished, namely the fourth, in which the thecae have strongly curved 

 ventral walls and markedly introverted and introtorted apertures, is repre- 

 sented in our fauna. Its type is I), nicholsoni. The forms here 

 noticed are : 



Dicranograpt us nicholsoni 



var. p a r v a n g u 1 11 s 



var. d i a p a s o n 

 D . ramosus 



var. arkansasensis 

 D . spinifer 



var. geniculatus 

 D. furcatus 



var. e x i 1 i s 

 D. con tortus 



Dicranograptus nicholsoni Hopkinson 



Plate 20, figures 3, 4, 5; plate 21, figure 1 



Dicranograptus nicholsoni Hopkinson. Geol. Mag. 1870. 7:357; pi. 16, fig. 3 

 Dicranograptus nicholsoni Lapworth. Cat. West. Scott. Foss. 1876. p. 6; 



pi. 3, fig. 79 

 Dicranograptus nicholsoni Lapworth. Belfast Nat. Field Club. Rep't & Proc. 



Apx. 1877. v. 1, pt 4, p.141; pi. 7, fig. 2 

 Dicranograptus nicholsoni Gurley. Jour. Geol. 1896. 4:297 

 Dicranograptus nicholsoni Tullberg. Sver. Geol. Und. Ser. C, no. 50. 1882. 



p. 20 

 Dicranograptus nicholsoni T.S.Hall. Roy. Soc. Victoria Proc. 1905. 18:24; 



pi. 6, fig. 7 . 

 Non Dicranograptus nicholsoni Roemer & Freeh. Lethaea Pal. 1897. 1:617, 



fig. 181 

 Dicranograptus nicholsoni Elles & Wood. Monogr. Brit. Grapt. pt 4 (Pal. 



Soc. 1904) p. 17 1, pi. 25, fig. ja-h 

 Dicranograptus nicholsoni T. S. Hall. Rec. Geol. Sur. Victoria. 1906. v. 1, 



pt 4, p. 274 



Description. Rhabdosome consisting of short biserial portion (quite 

 uniformly 5 mm long, with variations to 4 and 6 mm) and long uniserial 

 branches, attaining a length of 130+ mm and forming an axillary angle 



