ORAPTOLITES OF NEW YORK, PART 1 719 



being united in the center by a funicle and a central disk [p,528], and that 

 from the latter originate the gonangia in which new siculae are produced ; 

 and Wiman has shown that the apparent biserial arrangement of the thecae is 

 produced by one series, the thecae budding alternately on opposite sides 

 [p.538]. 



Diplograptus dentatus Brongniart sp. 



Plate 17, figures 10-13 



Fucoides deutatus Brongniart. Hist. Veget. Fobs. 1828. l:70ff, pl.6, 



fig.9-12 

 Grap t 1 i t h u s pristiniformis Hall. Geol. Sur. Can. Rep't. 1857. 



p.l33 

 Diplograptns pristiniformis Hall. Geol. Sur. Can. decade 2, 1865. 



p.llOff, pl.l3, fig.15-17 

 Diplograptns pristiniformis Nicholson. Quar. Jour. Geol. Soc. 1868. 



24:140, pi. 5, fig.l4, 15 

 Diplograptns dentatus Hopkinson & Lapworth. Ibid. 1875. 31:656flf, pl.34, 



lig.5a-k 

 Diplograptns dentatus Ami. Geol. Sur. Can. Rep't, ser.2. 1889. v.3, pt 2, 



p.ll7k 

 Diplograptns dentatus Gurley. Jour. Geol. 1896. 4: 298 

 Diplograptns dentatus Elles. Quar. Jour. Geol. Soc. 1898. 54:617ff 

 Diplograptns dentatus Ruedemann. N. Y. State Paleontol. An. Rep't. 1902. 



p. 570 



This type, which is very common in the graptolite beds at the dam in 

 the Deep kill section and at Mt Moreno, not only presents a great variety 

 of appearances, some of ^vhicll are represented by the camera tracings but also 

 considerable variations in its dimensions. 



Description. The rhabdosomes are as a rule narrow, attaining their full 

 width (1 . 8 to 2 . 1 mm) at an early stage of their growth, and maintaining this 

 throughout. Perfect specimens attaining a length of 45 mm have been 

 observed, but fragments indicate that they grew still beyond that size. The 

 thecae are closely arranged ; they number 10 in 10 mm in most specimens, but 

 in the earliest parts of a few numl)er 14 to If! and in the later portions of 



