GRAPTOLITES OF NEW YORK, PART 2 2/1 



Amphigraptus divergens (Hall) 



Plate 15, figure 2 



Graptolithus divergens Hall. Pal. N. V. 1859. 3: 509, fig. 9 

 .G rap t o 1 i t h u s divergens Hall. N. Y. State Cab. Nat. Hist. 12th An. Rep't. 1859. 



P-57. fig- 9 



Graptolithus d i v e r g e n s Hall. Can. Org. Rem. Dec. 2, 1865. p.isf, fig. 1 1 

 Graptolithus (Co e n o g rap t u s) divergens Hall. N. Y. State Cab. Nat. Hist. 



20th An. Rep't. 1868. p-179, fig. 12 

 Amphigraptus divergens Lapworth. Geol. Mag. 1873. IO: 559 

 Amphigraptus divergens Lapworth. Cat. West. Scott. Foss. 1876. p. 5; pi. i, 



fig. 70 

 Amphigraptus divergens Lapworth. Quar. Jour. Geol. Soc. 1878. 34: 331 

 Amphigraptus divergens Lapworth. Ann. & Mag. Nat. Hist. 1880. 6:18 

 Graptolithus divergens Walcott. Alb. Inst. Trans, v. 10. 1883. (Advance 



sheet. 1879, p. 35) 

 Amphigraptus divergens Lapworth. Roy. Soc. Can. Trans, v. 5, sec. 4. 1886. 



p. 1 84 

 Amphigraptus divergens Walcott. Geol. Soc. Am. Bui. 1890. 1:338 

 Amphigraptus divergens Gurley. Jour. Geol. 1896. 4:296 

 Coenograptus (? Pleurograptus, ? Pterograptus) divergens Roemer & 



Freeh. Lethaea Pal. 1897. 1:587 

 Amphigraptus divergens Elles & AVood. Monogr. Brit. Grapt. pt 3. 1903. 



p. 1 22; pi. 18, fig. 1 



Description. Rhabdosome of medium size, consisting of two straight 

 or but slightly curved main stipes, diverging at about 180° from the sicula 

 and several (as many as five) pairs of secondary branches, all of which 

 are produced in close proximity to the centre. The main and secondary 

 branches are thick (.8 mm-i mm wide) of uniform width and rigid appear- 

 ance. The sicula and primary thecae have not been made out ; the thecae 

 of the branches are very long (2 mm), number 8 to 10 in 10 mm, are six 

 times as long as wide and overlap more than one half their length. Their 

 free ventral margins are straight, the apertural margins introverted and 

 opening within shallow and short excavations. 



Position and localities. Hall records the form from the ''shales of the 

 upper part of the Hudson river group," giving no locality. His types came 



