scHucHEKT.] TABLES OF NORTH AMERICAN SPECIES. 



Table IV, — 07'ilovician liraohiopoda — Contiuued. 



35 



Species. 



Eoordovician. 



Calcifer- nv.^.„ 



0U8. ^•'»*y- 



Triplecia nucleus Hall 



Tripleoia ( ') radiata 'Whitfield 



Triplecia ulrichi "V\'incliell and Schuchert 



Zygospira cinciniiaticnsis Mock 



Zygospira concenlrica Ulrich 



Zygospira deflecta (Ilall) 



Zygospira exigua (Hall) 



Zygospira kentuckiensis James 



Zygospira niodesta Hall 



Zygospira nicoletti Winchell and Schuchert 



Zygospira putilla Hall and Clarke 



Zygospira recurvirostra (Hall) 



Zygospira saffordi "Winchell and Schuchert 



Number of Ordovician species, 319. 



Number of species in each division 



N umber of species common t» the Calciferous and the other 



divisions 



Number of species common to the Chazy and the other 



divisions 



Number of species common to the Trenton and the other 



divisions 



Number of species common to the Cincinnati and the other 



divisions 



Species common to the Ordovician and Silurian systems, 5. 

 Number of species passing from each division into the 



Silurian 



Mesoordo- 

 vician. 



Trenton, 

 Black River, 

 Birdseye 



128 



Neoordo- 

 vician. 



Cincin- 

 nati, 

 Utica. 



Ci 



Ci 

 Ci 



Ci 



U, Ci 



Ci 



136 

 1 

 2 



27 



