58 



Report of the State Geologist. 



evident. This is seen in lists from stations along the west shore of Seneca 

 lake (XV, XV 1 , XV 2 , XVI, XVII). At Belknap's Gully, two miles north of 

 Branchport, Yates county, the fauna has, so far as observed, virtually lost 

 its Ithacan component and presents only species abounding in the Naples 

 section. 



Now and then among the fossils in the Ontario and Livingston county 

 sections will be found a straggler from the east; Orihoihetes arctostriata, 

 Liopteria laevis and Strophalosia ttmiicata are among the less frequent forms. 

 The pelagic Styliolina Jissurella has been swept in in enormous quantities. 

 Chonetes s< , itnl<i and AmbocosUa umbonata are occasionally seen. With the 

 exception of Styliolina, these are all of unusual occurrence, and we have 

 evidence that such isolated representatives of the Ithaca fauna are to be 

 found in the Naples fauna as far westward as Erie county. 



The boundary lines of the Portage series of rocks have been, by the 

 labors of Mi-. I). I). Luther and the writer, made out with precision in 

 Ontario and the adjoining counties. In the Naples section the vertical thick- 

 ness of these rocks from the Genesee shales to top of the Portage sandstones 

 is 600 feet. These heavy-bedded Portage sandstones were regarded as the 

 upper boundary of the Portage series in the original delimitation of the 

 group, and they form a well denned bench mark throughout western New 

 York, but in more westerly sections they are overlaid by a considerable mass 

 of flags and sands which continue to carry a Naples fauna with some modifi- 

 cations, but embracing no typical Chemung species. 



The faunules of the beds lying immediately below the heavy sandstones 

 arc, in interesting respects, unlike those of the more prolific beds below. Thus 

 in Naples village, at a distance of twenty feet below these beds, are shales 

 w ith a Naples faunule, viz. : Buchiola speciosa, Bactrites, Palceoneilo muta, 

 ('<//■(//'<>/</ sj). Pleu rotoma via capillaria, Manticoceras Patersoni. Just below 

 the heavy-bedded sandstones comes in a faunule unlike anything observed 

 beneath, in this section; abundant in individuals though not in species, viz.: 

 Zdorhynchus, w hich at maturity is of large size and has the aspect of 

 quadricostaPiis, while younger shells resemble L. limitari* of the Marcellus 

 shales; Atrypa reticularis of small size witli coarse plications, and three or 

 four strong concentric varices, free at their edges; Productella speciosa, Lep- 

 tostrophia mucronata and an Orbiculoidea, probably undescribed. Evidently 

 this faunule has entered from the east, and it heralds the dispossession of the 

 Naples fauna and the occupancy of the region by wholly distinct types 

 of life. 



