42 



SYNOPSIS OF AMERICAN FOSSIL BRACHIOPODA. [bull. 87. 

 Table \. — Silurian Brack iopoda — C'oiitiuuetL 



Species. 



Zygospira ( ?) minima Hall 



Zygospira ( ?) paupera BilliDgs 



Number of Silurian species, 311. 



Number of species iu eacb division 



Number of species common to the Medina and the other 

 divisions 



Number of species common to the Clinton and llie other 

 divisions 



Number of species common to the Niagara and the other 

 divisions 



Number of species common to the Neosilurian and the other 

 divisions 



Species common to the Silurian and Devonian systems, 5. 



Number of species passing from each division into the De- 

 vonian 



Eo- 



silurian. 



Mesosilurian. 



N eosi- 

 lurian. 



!„,; o.-^ir.!, Tentac- 



Anti- Guelph, ,., 



Medina. costi, Ansaig, I x.7„f„l 



Clinton. Niagara. } y-^^^"^' 



116 

 



195 

 



