528 



KEW YORK STATE MUSEUM 



the earlier authors, Avhile the others continue to bifurcate, forming the 

 so called stems. Both kinds of branches consist of thecae. 



The early stages of all multiramous Dichograptidae are identical with 

 those of Goniograptus. 



A third series of growth stages, found in the New York rocks, is that of 

 Diplograptus foliaceus. This again is representative of the axono- 

 phorous Grajptoloidea and differs fundamentally from either of the two 

 mentioned before. It has been fully described and figured in the 14^tli 



a 



rig. 9 (1-8) Diplograptus foliaceus McCoy. Series of growth stages, g, g'onangium ; /;n, pneu- 

 matophor ; I, first generation of rhabdosomes ; II, second generation (Cop^- from Ruedemann) 



Anmiol Report of the New Yorli, State Geologist [pi- 3]. We copy here the 

 drawings of some of the most characteristic stages. These show that the 

 growth of the synrhabdosome of that diplograptid also begins with a sicula 

 provided Avith nemacaulus and disk [see fig.9]. 



From the sicula originates again a single theca [see fig. 9-2]. This, as 

 Wiman has demonstrated [see fig. 10] grows for a short distance downward 

 in the direction of the sicula, but then turns abruptly aside and the next 

 theca grows upward along the sicula in a proximal or antisicular dii'ection 

 and turns to the opposite side of the sicula. A continuation of this process 

 of budding and alternate arranging of thecae produces the first stipe, which 

 apparently consists of two separate series of thecae [see fig.9— i]. 



