388 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



five (see Table VIII.). In the Hamilton and Chemung, Brachiopoda 

 are predominating forms. 



Three typical Goniatites appear in the Portage, the Chemung 

 having only one, and that new. The eminently Devonian Cepha- 

 lopod, Clymenia complanatal (Van. and Hall), shows itself here ior 

 the first time, with the TJngulina suborbicularis (Hall). 



Cashaqua Shale contains, as common (and typical, except Gonia- 

 tites sinuosus), Avicula speciosa, TJngulina suborbicularis, Bellero- 

 phon expansus (Marc. Shale), Orthoceras aciculum, Clymenia com- 

 planata, Goniatites sinuosus, Pinnopsis acutirostra, P. ornata (Hall, 

 Rep. p. 243). 



The following are in the more central parts of the group : — Spi- 

 rifer Icevis, Cardium 1 vetustum, Orthis tenuistriata, Lucina 1 re- 

 tusa, Nucula lineolata, Astarte subtextilis, Bellerophon striatusl, 

 Goniatites bicostatus, G. sinuosus, G. retrorsus, Cyathocrinus orna- 

 tissimus, — the principal forms being Goniatites, Bellerophon, Pteri- 

 ncea, and a typical Avicula (Hall, Rep. p. 245, and De Vern. loc. cit.). 



The Portage group only received one Brachiopod and one Gaste- 

 ropod. It transmits the same bivalve, and a single Cephalopod. 

 Its fossil-connexion with other strata is therefore very slight. We 

 see the same partial distribution of life in the Upper Devonian of 

 England. 



Fossils typical. — These are nineteen in number, and are spread 

 through seven orders. 



Fossils occurrent in Europe. — Until we hear further from James 

 Hall, we only know of two, — the Devonian Goniatites retrorsus of 

 Nassau, and Atrypa dumosa. 



Fossils recurrent in New York. — These are only four, — Bellerophon 

 striatus (Cornif. limest.), B. expansus, Clymenia complanata (Che- 

 mung), and the almost universal Atrypa reticularis. 



Chemung Group. 



Mineral Character. — This is a highly fossiliferous series of shales 

 and thin-bedded sandstones, sometimes in distinct courses, and in 

 infinite variety both vertically and laterally, from the intermixture of 

 the two ingredients. This thin- or thick-beddedness depends on the 

 purity of the materials, on the proportion of clay, and on rate of 

 deposition. 



These rocks may be described as thin-bedded sandstones or flag- 

 stones, with intervening shales, and frequently with beds of impure 

 limestone resulting from the aggregation of organic remains (Hall). 



The whole series weathers brownish olive. The shales pass from 

 deep black to olive-green. The sandstones vary from brownish grey 

 and light grey to olive. Lines of diagonal lamination and ripple- 

 marks are common. 



The upper part of the group tends to be a conglomerate; and 

 here and there it is a true, but very thin, puddingstone, with the 

 usual fossils (Hall). 



