42S \K\V YORK STVTF. ArT>JFT\r 



deop(*r waters wore laid down contemporary deposits, wliich 

 doubtless included a richer congeries of orf^anic forms. What 

 these deeper wat«*r deposits Avere, where they are and what 

 they contained are facts necessary to ascertain before we can 

 arrive at a precise conception of the succession and correlation 

 of our Cambric deposits. In a supplementary chapter Mr van 

 Ingen has g:iven a brief summary of his season's work on this 

 problem. 



Limestone lenses in the Clinton beds. In previous reports record 

 is made of the fact that one of the problems under interrupted 

 investijration by the department, is that relating to the origin 

 of the peculiar lenses of unstratified semicrystalline limestone 

 which have been observed at various outcrops along the Nia- 

 gara cuesta from Lewiston to near Rochester. These lenticular 

 masses of large size, often fully 80 feet in diameter, are either 

 embedded in the well stratified and clearly jointed Clinton lime- 

 stone, or li<* near the upper surface of that limestone and are 

 overlain by the shales of the Rochester beds. The occurrence 

 of these peculiar rock forms, recorded first by r)r E. N. S. 

 Ringueberg of Lockjmrt and subsecjuently noted by G. K. Gil- 

 bert, their nature, origin and faunal composition have been 

 the subject of study; and it has before been noted that a series 

 of these rock bodies begins near Lewiston on the line of the 

 Rome, Watertown i^- Ogdensburg raihM)ad, where several are 

 exposed, are seen also in beautiful display on the rock face 

 along the line of the New York Central railroad just south of 

 Lewiston, also at Gasport in considerable number, and at Mid- 

 dleport. Dr Ringueberg's early observations on the faunal con- 

 tents of this peculiar rock served to indicate an association in 

 some degree foreign to that of the rocks with which it is most 

 intimately associat«Ml but with which it is never blended. The 

 fauna is not that of the Clinton rocks of New York nor of the 

 Rochester shales; though carrying a considerable representa- 

 tion of these faunas, its most conspicnons species are those 

 which have been described as occurring in western faunas 

 usually ascrib«*d to tli*' Xiagara grouj>. The obs<'rvations on 



