256 NEW YORK STATE MUSEUM 



about yifi inch and there are 24 cells in an inch. The substance of the 

 graptolite is green and coriaceous. This beautiful species occurs in Augusta 

 county, Virginia, in soft whitish shales. 



Gurley remarks to this species in his manuscript : 



This is a most wretched species, founded upon the worst possible 

 material. It has every appearance of consisting of accidentally juxtaposed 

 fragments of two (possibly, perhaps probably, distinct) Didvmograpti. 

 Nothing at all can be determined in regard to it until collections are 

 available from the type locality. 



Diciymograptus rectus (Emmons) 



Monograpsus rectus Emmons. Am. Geol. v. 1, pt 2. 1856. p. 107, fig. 28 



Original description. Straight, serrations pointed, upper edge of a 

 serration oblique to the axis of the stem. Width of a serration equals one 

 half of the width of the undivided part of the stem; width of the stem y% 

 inch, and 22 crenulations in an inch, whose edges are perfectly straight and 

 not curved so as to leave a curved space between the notches. 



From the point of each crenulation there runs an oblique ridge which 

 meets a longitudinal one, the latter runs nearer the straight than the crenu- 

 lated margin. This species occurs in Columbia county, in the Taconic 

 shales and is closely allied to G. latus of McCoy. 



Gurley remarks to this species : 



This species is without doubt a Didymograptns. Beyond this nothing 

 at present can be said. 



We may add that, since the type has been lost, and the description and 

 figure are not sufficient for identification — especially if it is taken in consid- 

 eration that in Columbia county graptolite shales from the Beekmantown 

 to the Trenton horizons are exposed and the form in question may have 

 come from any of these horizons — , it would seem most practical to drop 

 this unrecognizable species altogether. 



AZYGOGRAPTUS NicholsOU 



The trend of development of the great graptolite family Dichograp- 

 tidae has been a most peculiar one, as we have fully set forth in Memoir 7 

 [see ibid, p.553]. The family began with highly multiramous forms and 

 progressed steadily through various stages to forms with less and less 

 branches. The last stage noted in the lower graptolite beds of this State 



