REPORT OP THE STATE PALEONTOLOGIST 1902 



1159 



retreats, and next in the black Pittsford 1 shale at the base of the 

 Salina there occur Eurypteri, and with them constantly asso- 



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Fig. 5 Cycle of events showing the culmination and decline of the Salina sea 



dated a species of Lingula. With the retreat of this fauna we 

 find, as physical changes went on, deposits of gypseous shales 



^ 1 The Pittsford shale, which is exposed in the vicinity of Pittsford, Monroe 

 cb., is very dark and fragile, checking rapidly in drying. Intercalated in this 

 shale are thin layers of gray dolomite carrying species similar to Leperditia 

 s c a 1 a r i s Jones and Pterinea subplana Hall. Leperditia scalp- 

 ris is a characteristic species of the Cobleskill in Erie co., while P. subplana 

 appears to be represented in the Cobleskill of the Schoharie section. The 

 eurypterid and pterygotid species of the Pittsford shale are described by Mr C. 

 J. Sarle in the annual report of the state paleontologist, of which this paper 

 forms a part.^ 



