GRAPTOLITES OF NEW YORK, PART 2 399 



Champlain and in collections from Holland Patent, N. Y. and the neighbor- 

 hood of Floyd, N. Y. In all these localities it is associated with typical 

 Utica fossils ami it has not been found in either the underlying or overlying 

 formations. 1 It also has been identified in a collection from the Diplograptus 

 bed in Elgin, la. (zone of Asaphus g i ga s-i o w ensis). 



Remarks. This minute form was originally referred by Hall to his 

 genus Retiograptus and described and figured as having the "cell partitions 

 alternating, essentially rectangular to the axis," which is a direction of thecal 

 growth quite different from that of other graptolites. It was the only 

 diprionid form known then to grow in compound colonies (synrhabdosomes). 



When the present writer, a few years ago, had an opportunity to see 

 authentic specimens of this species from the original locality, he found them 

 to possess a typical Diplograptus structure and to show in the majority of 

 the rhabdosomes the usual inclined thecae of a Diplograptus. The facts in 

 the case are hence the following : the draftsman has taken the peculiar state 

 of preservation of some rhabdosomes, in which the apertural margins of 

 both series of thecae are shown on both sides of the axis, as the normal 

 state of preservation and extended this upon the whole colony. Professor 

 Hall drew up his description of this very small graptolite from the drawing, 

 as I have since learned from Professor Whitfield, thereby mistook these 

 apertural margins for the cell partitions and thus came to assign the form 

 as a peculiar type to Retiograptus. For this reason the species has failed 

 to be recognized by subsequent authors, though Hall's figures had been 

 frequently copied and the form has a wide distribution. The present writer 

 wrongly identified his material with Diplograptus pristiniformis 

 and Dr Gurley upon receiving material from me and perceiving this 

 error described it as a new species, while Freeh compared it to D . 

 aculeatus Lapworth. 



'This statement may need qualification in regard to the occurrence at Sandy Hill, 

 N. Y., where this species has been obtained at a recent visit in an association indicating a 

 somewhat greater age of the beds \see p. 31]. To the list of Sandy Hill forms Diplo- 

 graptus foliaceus is to be added. 



