REPORT OF THE STATE PALEONTOLOGIST 1902 865 



Other field work. Mr Richard F. Morgan has made for 

 us some collections in the Marcellus limestone, temporarily ex- 

 posed at Stony point south of Buffalo, at a time when such 

 collections were much needed. Mr H. S. Mattimore has also 

 collected to some extent in the Black river limestone in Jefferson 



county. 



Office work 



Memoir on the Guelph fauna in the State of New York. Ref- 

 erence is made on a previous page to the field work done 

 during the past season with reference to these investigations. 

 We have brought together in the memoir now in press a detailed 

 account of this fauna, which, in New York, has risen to the 

 very considerable representation of 70 species. It has been 

 shown that this characteristic Guelph fauna, constituting vir- 

 tually a new element in the Paleozoic limits of the State, entered 

 from the west, penetrating as far east during the period of the 

 deposition of the Magaran dolomites as eastern Orleans county, 

 and then retreated, reappearing after an interval in which some 

 30 to 40 feet of Niagaran dolomites had been deposited, and in 

 the second invasion reaching as far east as the vicinity of 

 Rochester. This second appearance of the fauna was less com- 

 plete in species than the first, and its horizon lies at or very 

 close to the summit of the dolomites, making thus a phenomenon 

 pertaining to the closing stage of the dolomite episode. The 

 little cluster of fossils of this fauna, which were reported as 

 long ago as 1843 by Professor Hall from the Erie canal at 

 Newark, Wayne co., a locality from which nothing more has ever 

 been obtained, seems to have come from a still higher horizon 

 within the basal deposits of the Salina shales, where, under 

 unfavorable conditions, the impoverished representation of the 

 Guelph fauna made its final appearance. The consideration of 

 this fauna, which is illustrated by 21 quarto plates, involves 

 the analysis and discussion of the nature of the sea and of the 

 sediments of the Guelph period of time; and we have shown 

 with reasonable conclusiveness that these deposits are ascrib- 

 able to coral reef formations occurring in an inclosed and shal- 

 lowing sea, which was gradually approaching the conditions 

 essential for the free precipitation of salt and gypsum, such as 

 prevailed during the succeeding Salina stage. The sea was one 



