HUDSON RIVER BEDS NEAR ALBANY 547 



One fossil of the Rysedorph hill fauna deserves special notice 

 in this place. It is a small graptolite, several specimens of which 

 were found in an exquisite, uncompressed state of preservation 

 in a small, dark gray limestone pebble which within a cubic inch 

 contained, besides the graptolites, a cranidium of A m p y x h a s - 

 t a t u s , a cephalon of Pterygometopus calli- 

 cephalus, Plectambonites aff. g i b b o s a and a 

 Callopora {see pi. 1, fig. 1). The graptolite is a Glima- 

 cograptus. A careful comparison of it with all the spe- 

 cies of Climacograptus obtained so far from the Nor- 

 mans kill and Utica shales of New York shows its absolute iden- 

 tity with a form which is quite common in the Normans kill 

 shale of Mt Moreno near Hudson. It differs from all other epe- 

 cies of Climacograptus by its strong sculpture and 

 specially by the characteristic deep, strongly zigzag groove 

 along the median line of the rhabdosome. This is a character- 

 istic feature of Climacograptus s c h a r e n b e r g i Lap- 

 w^orth, with which it also agrees in the rectangular outline of 

 the thecae and apparent absence of appendages. 01. scharen- 

 b e r g i has been reported before by Lapworth and Gurley from 

 the lower and upper Dicellograptus zones (the former=Normans 

 kill zone) of Canada. It does not rise into the Utica and Lor- 

 raine beds. Its association at Rysedorph hill with a peculiar 

 lower Trenton fauna, is, hence, a strong argument in favor of 

 the lower Trenton age of the Normans kill shale. 



In Europe this graptolite occurs at even deeper horizons; for 

 Roemer (54:612) collected it in the Phyllograptus shales near 

 Christiania, and Tullberg reports it from the horizons with 

 Didymograptus geminus and Diplograptus 

 putillus, which, in Scania, lie below the Coenograptus 

 gracilis zone (=lower Dicellograptus zone). In Scotland it oc- 

 curs in the corresponding Glenkiln shales, which also lie deeper 

 than the zone with Coenograptus gracilis which forms 

 the base of the Moffat beds. 



The beds on Rysedorph hill which outcrop at the fault be- 

 tween the Normans kill shales and the Cambrian slates repre- 



