GRAPTOLITES OF NEW YORK, PARI' 2 |^l 



Pterygoraetopus call icephal us in a black limestone pebble of the 

 Rysedorph conglomerate, which is intercalated in Normanskill shale. This 

 specimen must be hence of greater than Normanskill age and probably 

 belongs to a subzone not yet recognized (approximately of Black river age). 

 The museum collection from the Normanskill shale of Glenmont near 

 Albany, contains a slab that is covered with a great number of rhabdosomes 

 of this species, in association with C 1 i m . b i c o r n i s and D i p 1 . f o 1 i - 

 aceus. Other specimens have been found at Mt Moreno near Hudson. 



Remarks. The most characteristic feature of this species is seen in 

 the deflections of the sutural groove and the short horizontal grooves 

 proceeding from the outer angles of the former. This structure is well 

 shown in text figure 399, taken from a specimen which though somewhat 

 compressed, has not lost ail relief. The latter and that from Rysedorph 

 hill [text fig. 397] which is preserved in full relief, show that the short 

 horizontal grooves mark the budding places of the new thecae. They 

 also indicate that the proximal part of the theca is not strictly parallel to 

 the nemacaulus but corresponding to the zigzag sutural groove inclines 

 first inward, then turns at an angle of about 140 obliquely outward and in 

 the last, distal part assumes a direction parallel to the axis of the 

 rhabdosome. 



From C. parvus this species differs, aside from the markedly 

 deflected groove, in the more gradual widening of the rhabdosome. In a 

 strongly compressed state the two are similar, but the remarkably deep 

 notches or apertural excavations, which separate the narrow, rectangular, 

 free ends of the thecae, instead of the square ones of parvu s, will always 

 permit a separation. The connection between the full relief specimens of 

 C. scharenbergi from the Rysedorph hill conglomerate and the very 

 dissimilar, much compressed films from the Normanskill shale at Glen- 

 mont is formed by a few specimens in demirelief condition found at Mt 

 Moreno [see fig. 399]. 



