44 



Report of the State Geologist. 



represented in the Ithaca beds elsewhere : HyoUihes acUs, Strophahsia 

 truncata, PTwlidops Hamiltonice, I/mgula ligea, var. (Hall), and some others. 

 Above these beds comes in a more extensive and pronounced Hamilton fauna 

 containing PJiacops rami, Spirifer nmcronatus (the Hamilton type of the 

 species), Spvrifer asper, Atrypa reticularis (large and finely plicated), Ithipkl- 

 omella Vanuxemi, Actinopteria Boydi (strictly the Hamilton form), and some 

 others of wider range into the higher beds of the group. While we may speak 

 of these associations of fossils as recurrent appearances of the Hamilton fauna, 

 this is not an accurate expression, for there appear associated with such 

 species as the above, others which serve to demonstrate that this fauna lying 

 above the lower Portage beds (Sherburne sandstones) is a Hamilton fauna 

 modified by the introduction of certain species and variations foreign to the 

 normal fauna of the Hamilton group. One of the most striking witnesses of 

 this modification is the presence of Leptaena rJiomboidalis, found at Station III; 

 of a large and abundant new species of Oyrtina ; of Poteriocrin us gregarius, 

 Actinopteria zeta and A. perstrialis. The association of species is constantly 

 varying through the different horizons of these rocks ; some of them are 

 restricted in their range, e. g. PJiacops rana, Homalonoius DeKagi, Spirifer 

 asper, and the fossiliferous horizons were generally widely separated by inter- 

 vals of barren rocks. It is noteworthy that the species Phacqps rana and its 

 associates, which evidence strong Hamilton characters, are less abundant 

 and much more sharply restricted in the Otselic valley sections where the 

 whole series is separated from the true Hamilton beds below by the Genesee 

 shale and Tully limestone, than in the Chenango valley, as at North Norwich 

 and Norwich, where those beds have totally disappeared from the section. 



Ithaca Group (upper division). 



The distinctive difference in the lower and upper faunas of the Ithaca 

 group is due to the introduction of Spirifer mesastrialis. So far as my own 

 observations extend, and I believe they are confirmed by those of Professor 

 Prosser, this species does not appear in the lower beds. Its first appearance 

 a1 South Otselic was found by Prosser at 585 feet above the valley, which is 

 essentially the same distance above the top of the Sherburne sandstones. Its 

 associated fossils have more or less strongly developed Hamilton characters as 

 shown by the species recorded from sections in the village of Cincinnatus, 

 Cortland county (Station V, 1894); near Pitcher, Chenango county (Station 

 T) : at Solon, (Station VIII); in the vicinity of McGrawville (Station IX 1 ); 



