TRENTON CONGLOMERATE OF RTSEDORPH HILL 89 



probable, that the long, leaf-shaped plate figured by the writer 

 represents this plate of the exoskeleton of Lepidocoleus 

 jamesi, and that the apparent carina is the reverse side of 

 that groove. Several specimens of this type of plate structure 

 have been observed by the writer. 



Dr Woodward has described 1 a species of Turrilepas, obtained 

 by Dr Ami in the lower Utica beds of Ottawa, as Tur- 

 rilepas canadensis. This species is quite certainly not 

 identical with the one represented by the Trenton and Utica 

 specimens of the vicinity of Albany, referred to Lepidoco- 

 leus jamesi, for its plates are about three times as large 

 as those of the latter, and differ materially in shape; the carina 

 also lies not medially but close to the longer side. (Group 5) 



ANALYSIS OF THE FAUNA OF THE CONGLOMERATE 



Fossils contained in the various kinds of pebbles 



c=common; cc=very common; r=rare; rr=very rare 



GROUP 



1 Gray limestone 



Hyolithellus micans Billings 



2 Gray and reddish sandstone 



None 



3 Black crystalline limestone (Chazy limestone) 



Bolboporites americanus Billings 

 Palaeocystites tenuiradiatus Hall sp. 



4 Lowville limestone 



Tetradium cellulosum Hall sp. 



5 Black compact limestone 



Streptelasma corniculum Hall c 



Diplograptus foliaceus Murch. sp. r 



Climacograptus scharenbergi Lapworth r 



Stomatopora inflata Hall sp. c 



Stictopora cf. elegantula Hall r 



Callopora multitabulata Ulrich cc 



Sipliojiotreta minnesotensis Hall & Clarke' rr 



Crania trentonensis Hall r 



Rafinesquina alternata Emmons sp. c 



Leptaena rhomboidalis Wilckens c 



Plectambonites sericeus Soicerby sp. c 



P. pisum sp. nov. cc 



* Geol. mag. 3d ser. 1889. 26: 274. 



