GRAPTOLITES OF NEW YORK, PART 2 



249 



the finding of specimens of sufficient length to show the direct and con- 

 tinuous connection of specimens of the dimensions of Hall's types with the 

 proximal parts will ever be accomplished, for from the rate ol growth 

 obtained from the long Mount Moreno specimens, we infer that the frag- 

 ment representing Hall's type must have been at least 2.5 mm distant 

 from the center. 



^<S^ 



151 



153 



Fig. 151-55 Oidyjnograptus sag i 1 1 ic au 1 i s Gurley. Fig. 151, 152 Portions of a proximal 

 fragment of branch from Glenmont. Fig. 153 Portion of Hall's type. Fig. 154. Dr Gurley's 

 original figure of D . convexus. Fig. 155 Portion of one of Dr Gurley's typesof D. convexus 

 from Stockport, N. Y. The originals of figures 151-53 are in the New York State Museum, those of 

 figures 154 and 155 in the National Museum. Fig. 154 Enlarged x ij£, the others x 5 



We insert here camera drawings of a portion of Hall's type, of the 

 initial and distal parts of D. convexus Gurley and of the intermediate 

 stages from Mount Moreno to show the gradual transition in characters. 

 This transition finds its clearest expression in the arrangement of the thecae. 

 While in the widest of the types, only seven to eight thecae are counted in 

 10 mm and in D. convexus nine in the same distance (at the distal 



