672 NEW YORK STATE MUSEUM 



Ithaca fauna. As a benthonic littoral congeries, chiefly of 

 lamellibranchs and brachiopods, it has acquired variation with 

 age, and, on the removal of the obstructions to migration which 

 prevailed in Ithaca time, it disseminated itself eastward to the 

 Catskill embayment, probably over it at times and westward 

 beyond the limits of the state. It also spread over the heart of 

 the gulf and along its southward shore. From this, its home 

 province and center of dispersion, departed, or to it were added, 

 certain widespread species,, such as Spirifer disjunc- 

 t u s and the glass sponges. It is however as a whole the last 

 expression of the single New York fauna of Devonic time which 

 may be properly characterized as indigene. 



