668 NEW YORK STATE MUSEUM 



Group 6 Not represented 

 Group 7 Type : D. c a d u c e u s 



D. caduceus I 



D. caduceus var. nanus f- Reclined series 



D. forcipifortnis 



D. incertus 



I 



Didymograptus extensus Hall sp. 



Plate 13, figures 17, 18 ; plate It, figures 1-4 



Graptolitlius extensus Hall. Geol. Sur. Can. Eep't. 1858. p.l32 

 Graptolithus extensus Hall. Canadian Organic Remains, decade 2. 1865. 



p.80, pl.2, fig.11-16 

 Graptolithus con strictus Hall ( pars). /6m?. p.76, pl.l, fig 23-27 

 Didymograptus e xtensus Nicholson. Ann. and Mag. Nat. Hist. ser. 4. 1870. 



4:341, pl.7, fig.2, 2a 

 Didymograptus extensus Hopkinson & Lap worth. Quar. Jour. Geol. Soc. 



1875. 3 1 :642, pl.33, fig.la-ld 

 ?Graptolites (Didymograptus) extensus McCoy. Geol. Sur. Victoria. 



Prodr. Pal. Victoria, decade 2. 1875. p.29, pi 20, iig.l, la 

 Cf. Didymograptus constrict us Linnarsson. 1879 

 Didymograptus extensus Brogger. Die sil. Etagen 2 and 3. 1882. p.40 

 Cf. Didymograptus con s trie t us Brogger. Ibid. 1882 

 Didymograptus extensus Herrmann. Geol. Mag. Dec. 3, 1886. 3:14 

 Cf. Didymograptus const rictus Herrmann. Ibid 

 Didymograptus e x tensus Lapworth. Roy. Soc. Can. Proc. and Trans. 1887. 



4:168, 184 

 Didymograptus extensus Ami. Geol. Sur. Can. Rep't, ser.2. 1889. v.3, 



pt2, p.ll6k 

 Cf. Didymograptus constrictus Ami. Ibid 



Didymograptus e x t e n s u s Roemer-Frech. Lethaea palaeozoica. 1897. 1:591 

 Didymograptus e xtens us Elies. Quar. Jour. Geol. Soc. 1898. 54:504 

 Didymograptus e x t e n s u s Tornquist. Lunds Univ. Arsskrift 1901. Bd 37, 



Af.2, Nr 6, p.l"}, pl.l, fig.25-30 

 Cf. Didymograptus co nst ric t us Tornquist. Ibid. p.l7, pl.2, fig.13-17 

 Didymograptus extensus Elles & Wood. Monogr. Brit. Grapt. ptl. Pal. 



Soc. vol. for 1901. p.8, pl.l, fig.la, b 

 Didymograptus extensus Rnedeminn. N.Y. State Paleontol. An. Rep't. 



1902. p.556 



