432 BULLETIN 92, UNITED STATES NATIONAL MUSEUM. 



Didyniograptus flliformls Tullberg. 



Didymograptus filiformis Tullberg, Geol. Foren. Stockh. Forh., 5, 1880, 42, pi. 2, 

 figs. 8-11. Lapworth, Ann. Mag. Nat. Hist., 5th ser., 6, 1880, p. 20. Brogger, 

 Die sil. Etagen 2, 3, 1882, p. 39. Tullberg, Sver. Geol. Und., Afh. och upps. 

 ser. C, 50, 1882, p. 22. Tornquist, Lunds Univ. Arsskrift, 37, Af. 2, nr. 5, 

 1901, pi. 3, figs. 6-9. Elles and Wood, Mon. British Grapt., pt, 1, Pal. Soc., 

 1901, p. 32, fig. 20. Ruedemann New York State Pal., Ann. Rep., 1902, p. 

 556; Mem. New York State Mus., 7, pt. 1, 1904, pp. 686, 687, pi. 14, figs. 

 8-14. 



Lower Ordovician : Scania, Westrogothia; Norway; Scotland (Arenig); Deepkill, 

 Rensselaer County, and Mount Moreno, near Hudson, New York (Deep- 

 kill, Tetragraptus and Diplograptus dentatus zones). 



Didymograptus forcipiformis Ruedemann. 



Didymograptus forcipiformis Ruedemann, Mem. New York State Mus., 7, pt. 1, 



1904, pp. 699, 700, pi. 15, figs. 10-13; text fig. 91. 



Canadian: Mount Moreno, Columbia County, New York (Deepkill, Diplograptus 

 dentatus zone); Point Levis, Quebec (Levis, D. dentatus zone). 



DIDYMOGRAPTUS FRUTICOSUS Etheridge. See Tetragraptus fruticosus. 



Didymograptus furcillatus Lapworth. 



Didymograptus furcillatus Lapworth, Quar. Jour. Geol. Soc. London, 31, 1875, p. 



649, pi. 35, figs. 3a-3d. 



Didymograpsus murchisoni furcillatus Gurley, Jour. Geol., 4, 1897, p. 97. 

 Ordovician: Wales (Lower Llandeilo) : Point Levis, Quebec (Levis). 



DIDYMOGRAPTUS GIBBERULUS Nicholson. See Didymograptus (Isograptus) caduceus. 



Didymograptus gracilis Tornquist. 



Didymograptus gracilis Tornquist, Under, ofver. Siljans. Graptoliter 1 (Aftryck ur 

 Lunds Univ. Arsskrift. 26), 1891, p. 17, pi. 1, figs. 9-12. Holm, Geol. Foren. 

 Stockh. Forh. 17, H 3, 1895, pi. 1, figs. 7, 8. Elles, Quar. Jour. Geol. Soc., 

 54, 1895, p. 506. Elles and Wood, Mon. British Grapt., pt. 1, 1901, p. 24, 

 pi. 2, fig. 2. Ruedemann, Mem. New York State Mus., 7, pt. 1, 1904, pp. 679- 

 681, figs. 15-21, pi. 14. 



Didymograptus (Leptograptus) gracilis Ruedemann, New York State Pal., Ann. 

 Rep., 1902, p. 589, fig. 17. 



Lower Ordovician: Dalarne, Sweden (Phyllograptus shales); England (Skid- 

 daw); Deepkill, Rensselaer County, etc., New York (Deepkill, Didymograp- 

 tus bifidus zone). 



Didymograptus incertus Ruedemann. 



Didymograptus sp. nov. Ruedemann, New York State Pal. , Ann. Rep. , 1902, p. 570. 

 Didymograptus incertus Ruedemann, Mem. New York State Mus., 7, pt. 1, 1904, 



pp. 700, 701, pi. 15, fig. 14, text fig. 92. 

 Canadian (Deepkill, Diplograptus dentatus zone): Deepkill, Rensselaer County, 



New York. 



Didymograptus indentus (Hall). 



Graptolithus indentus Hall, Canadian Nat. Geol., 3, 1858, p. 163; Geol. Surv. 



Canada, Rep. Progr. for 1857, 1858, p. 128; Geol. Surv. Canada, dec. 2, 1865, 



p. 74, pi. 1, fig. 20. 

 Graptolithus (Monoprion) indentus Hall, 20th Rep. New York State Cab. Hist., 



1868, p. 226; rev. ed., 1870, p. 260; p. 223. 



