Upper Devonian. 



522 HISTORICAL PALAEONTOLOGY. 



nian Rocks of the State of New York, in which, probably, the 

 series is most typically displayed : 



1. Oriskany period (Oriskany Sandstone),* \ 



2. Corniferous period (comprising the ( T 



Cauda-Galli grit, Schoharie grit, and / Lower Devonian. 

 Upper Helderberg group), 



3. Hamilton period (comprising the Mar- 



cellus, Hamilton, arid Genesee 

 groups), 



4. Chemung period (comprising the Por- 



tage and Chemung groups), 



5. Catskill period (Catskill Sandstone), 



LIFE OF THE DEVONIAN PERIOD. Taken as a whole, the 

 life of the Devonian period may be regarded as transitional 

 between that of the underlying Silurian and overlying Carboni- 

 ferous period. As far, however, as our present knowledge 

 allows of our forming a definite opinion, the Devonian fauna 

 and flora approximate more nearly to those of the succeed- 

 ing Carboniferous than to those of the antecedent Silurian 

 period. This is especially shown in the Devonian plants, 

 which, as has been already pointed out, in almost all cases 

 agree generically with those of the Carboniferous ; whilst 

 in some cases they are even specifically identical. Thus, the 

 Devonian land supported an abundant vegetation, in which 

 Lepidodendroids, Sigillarioids, Calamites, Ferns, and Conifers, 

 mostly of Carboniferous types, play a prominent part. There 

 are, however, some forms, which, like Psilophyton, are as yet 

 not known to have occurred in the Carboniferous deposits. 



The Protozoa are represented in the Devonian rocks byTvr- 

 aminifera and Sponges. Of the latter, Sparsispongia is the 

 most characteristic genus. (Steganodictyum is the buckler of a 

 Pteraspidean fish.) 



The Ccclenterata are represented by the Hydrozoal genus 

 Dictyonema, which has often been referred to the Graptolites, 

 and by very numerous and varied forms of corals. No true 

 Graptolites have been as yet detected, unless Dictyonema be 

 one. The corals still belong mainly to the groups of the 

 Rugosa and Tabulata. The section of the Tubulosa (Aulopor- 

 ida) is represented here for the first time. Here also occur 

 the singular operculate Rugose corals upon which the genus 

 Calceola is founded. 



The Echinodermata are represented in the Devonian period 

 by numerous Crinoids (Cupressocrinus, Aplocrinus, Platycri- 



* The Oriskany Sandstone, though here placed in the Devonian, is pro- 

 bably really the summit of the Upper Silurian. 



