Maryland Geological Survey 



119 



The relation of the species of the Keyser member to those of other 

 horizons is summarized in the subjoined table. 



Favosites 



.- Chotiftes heldbergiae 



iiipi'iiher jerseyensis var. prs- 



zotie cerlens 



zone 



No. Pet. No. Pet. No. Pet. 



Species occurring in other areas 73 45 61 49 19 53 



Species restricted to Maryland 91 55 63 51 17 47 



Total 164 . . 124 . . 36 . . 



Species occurring In Tonoloway 14 8 12 . . 3 .. 



Species occurring in both zones 10 6 10 . . 10 . . 



Range of species occurring in other areas (omit- 

 ting Atrypa reticularis and Leptwna rhomhoi- 

 dalis) : 



Decker Ferry of New Jersey 28 38 24 40 5 26 



Rondout of New Jersey 3 4 3 5 1 5 



Manlius of New Jersey 5 7 4 7 2 10 



Wilbur of New York 7 9 4 7 2 10 



Coblesldll of New York 11 15 10 17 3 16 



Rondout of eastern New York 8 11 7 12 2 10 



Rondout of central New York 6 8 4 7 3 16 



Manlius of eastern New York 4 5 3 5 2 10 



Manlius of central New York 5 7 4 7 2 10 



Coeymans, New Scotland and Becraft 31 43 19 30 12 63 



The preceding table shows that the fauna of tiie Chonetes jerseyensis 

 zone is more closely related to the Decker Ferry fauna of New Jersey than 

 to any other, a relationship rendered more pronounced by the character of 

 the species found in it, including Chonetes jerseyensis, Schuchertella 

 deckerensis, Stenochisma deckerensis, Cladopora rectilineata and various 

 other important members of that fauna. 



The fauna of this zone also shows a marked relation to that of the upper 

 members of the Helderberg, 30 per cent of the species not restricted to 

 the Keyser member being found in them. It also bears a less striking, 

 though close resemblance to the fauna of the Coblesldll, 17 per cent of the 

 species not restricted to the Keyser occurring in it. 



The fauna of the Favosites helderherg'uc prcecedens zone is still more 

 closely related to that of the overlying members of the Helderberg, 63 per 

 cent of its species being found in them. That it is older, however, than the 

 Coeymans to which Schuchert referred it is shown by the occurrence in it 



