GRAPTOLITES OF NEW YORK. PART 2 



! 45 



Two species were described, viz : P . brae h y m e r a, as the genotype, 

 and P . la e v i s. 



To test the validity of this new genus, we have to examine its species. 

 Of P . b r a c h y m e r a the following' figure and description are given : 



Greatest length observed, 175 mm; width 1 mm; number of segments 

 in 25 mm, about 18; each segment as long as, or little longer than wide 

 (rarely one and one half times as long) ; pit large. 



Horizon and locality. Lower Diccllograpsus zone, Stockport, N. Y. 



From this it can be inferred that the straight, simple margins, the seg- 

 mentation and pits are the essential, or only features of the 

 form. While we have not succeeded in finding Dr Gurley's 

 type of this species in the Stockport collection which we 

 have studied, other specimens showing exactly like charac- 

 ters as also like width and number of segments within 

 10 mm were found in the collection. These proved to be 

 identical with many others which before had been observed 

 by the writer- in other Normanskill collections and laid 

 aside on account of their peculiar aspect, but which invari- 

 ably turned out to be frontal views of the branches of a Fi g . i S o Ph y co g ra P - 



tus brachymera Gur- 



Dicellograptus. There is no doubt in my mind that this ££„ a£T r . Geoi. ^."*! 

 species also is based on such material. In fact., I have 

 before me specimens showing this aspect in one portion and that of a 

 Dicellograptus in another. The apparent segmentation is produced in 

 the flattening process of fossilization by the small interval between the 

 anterior overhanging apertural margin and the excavation for the aperture 

 in the next theca. When looked at in oblique light, the gradual rising of 

 the theca towards the aperture can be still distinctly seen. The entire 

 border is due to the rather large size of the common canal in Dicellograptus, 

 whose edges are shown on the sides of the frontal view and the large pits 

 are the internal apertures of the thecae, which shine through the perisark 

 and in like preservation can be seen in many other genera. There occur 

 in the same collection narrower Phycograptus — aspects corresponding to 

 other species of Dicellograptus. 



