TRENTON CONGLOMERATE OF RYSEDORPH HILL 11 



bolboporites Pander 

 Bolboporites americanus Billings. Can. nat. and geol. 1859. 4:429 



PL 1, fig. 1 

 This North American representative of the Russian Lower 

 Siluric genus Bolboporites is according to Billings character- 

 ized by " a solid hemispherical base surmounted by a coni- 

 cal projection which is celluliferous, the cells being about the 

 size and shape of those of the common S t e n o p o r a f i b r o s a." 

 Specimens collected in the Champlain region, about Valcour, 

 where this organism is extremely common in certain beds, show 

 that the celluliferous projection is somewhat variable and may 

 he ellipsoidal as in the specimen figured. While the taxonomic 

 position of this body appears to be still doubtful, its value as an 

 index fossil for the Chazy period is determined by the fact that 

 no other representative of this genus has thus far been found in 

 beds of any other period. According to Brainerd and Seely it is 

 restricted to the lower Chazy. Specimens of this species were 

 found at Rysedorph hill in pebbles of a black, crystalline crinoidal 

 limestone, associated with plates of Palaeocystites 

 tenuiradiatus Billings, another characteristic Chazy fossil. 

 (Group 3) 



DIPLOGRAPTUS McOoj 



Biplograptus foliaceus Murchison sp. 



G-raptolites foliaceus Murchison. Silurian system. 

 1830. p. 695 



A few rhabdosomes of this widely distributed and long-lived 



species w 7 ere found in the black limestone pebbles associated with 



Trenton fossils. (Group 5) 



CLIMACOGRAPTUS Hall 



Climacograptus scharenbergi Lapworth 

 C 1 i m a c o g r a p t u s. s c h a r e n b e r g i Lapworth, in Arm- 

 strong, Young and Robertson's Catalogue of west Scottish fossils. 



1876. p. 140 



PL 3, fig. 1 



Climacograptus scharenbergi, an easily recog- 

 nized graptolite, was found by Lapworth to occur in the lower 



