HUDSON RIVER BEDS NEAR ALBANY 539 



while an investigation of the rocks to the east of the Trenton 

 zone has furnished ample evidence of the presence of the 

 Dicellograptus zone. 

 The following stations with these fossils were found: 



Station 27. Cahill's hill, south Troy 



Behind the Brothers's quarry outcrops of mostly dark shales 

 may be followed up almost to the top of Cahill's hill, whence a 

 small gully runs north into the Poesten kill in upper Spring ave- 

 nue, south Troy (station 27). This gully furnishes a good section. 

 In its upper part greenish gray argillaceous shales, farther down 

 gray, somewhat sandy shales, and at the bottom softer, black 

 argillaceous shales are exposed. The last contain graptolites in 

 a fine state of preservation; besides Corynoides calicu- 

 1 a r i s and a narrow Diplograptus which closely ap- 

 proaches D. amplexicaulis; well developed specimens of 

 Diplograptus foliaceus occur in fair number. The 

 combined presence of these indicates the transition of the middle 

 Trenton shale of station 24 into another zone. 



Station 28. Poesten kill, South Troy 



The Trenton shales of the Brothers's quarry appear again acros-s 

 the Poesten kill in Spring avenue in a small road metal pit be- 

 hind the northern row of houses. Going from here 200 yards 

 east, along the north bank of the Poesten kill, just above Ruff's 

 canal mills, a four foot sandstone bed is met with to the left 

 of the road, which is overlain by black, strongly carbonaceous, 

 argillaceous, rather thick bedded shales. These were found to 

 contain graptolites in considerable number and in a fair state 

 of preservation (station 19). There were observed: 



Leptograptus subtenuis. Hall isp. 



Dicellograptus intortus, Giirley 



D. sextans. Ball sp. 



C'limacograptus bicornis, Hall 



C. parvus. Ball 



Diplograptus foliaceus, Mii/rcMson sp. 



