HUDSON RIVER BEDS NEAR ALBANY 505 



Walden, on tlie banks of the Wallkill, 11 miles northwest of New- 

 burgh on the Hudson, two localities in Orange county which were 

 m'entioned by Mather. The following fossils (according to Whit- 

 field's identification) were collected : O r t h i s p e c t i n e 1 1 a , 

 O. t estu din aria, O. plicate 11 a, Leptaena se ri- 

 ce a, a m a r e 1 1 a h e m i p 1 i c a t a, S t r o p h o m e n a la 1 - 

 tern at a, S t r ep t o r hy n ch us planumbona or S t r. 

 filitexta? and a Trinucleus c on c en t ri c u s. Be- 

 sides fragments of C h a e t e t e s or F a v o sites, a crinoidal 

 column and a fragment of C o n u 1 a r i a (probably t r e n t o n - 

 e n s i s ) . 



The greatest interest attaches to Orthispectinella, 

 andJ S t r e p t r h y n c h u Si p 1 a n u m b n a or filitexta, 

 as these forms indicate the Trenton age of that shale. 



I. P. Bishop 



While thus the fortunate discoYeries of fossils other than grap- 

 tolites in the " Hudson river shales " began to furnish evidence 

 ef the Trenton age of part of the shales, other investigations, 

 notably those of I. P. Bishop (33) tended to demonistrate the close 

 stratigraphic relationship of the Trenton limestone and the grap- 

 tolite-bearing Hudson river shales; for, in Columbia county, it 

 was established by Bishop that " the limestone containing Tren- 

 ton fossils immediately underlies the graptolite shales of the Hud- 

 son river group ''. 



Charles Lapworth , 



An entirely new course to the solution of the problem of the 

 age of the Normans kill fauna was entered on by Charles Lap- 

 worth (3^), who studied the graptolite faunas from numerous 

 localities, i^ Canada, and sought to determine their age by com- 

 paring them with the faunas of the detailed graptolite zones which 

 he had sio well succeeded in establishing in Great Britain. A 

 farther innovation in the mode of viewing the problem is implied 

 in Lapworth 's suggestion that the Normans kill graptolite beds 

 do not necessarily represent a separate stage in the series of forma- 

 tions but are probably equivalent with certain calcareous strata 



