14 



younger formations than the Silurian. Both vegetable and ani- 

 mal life existed in the Silurian seas, although no traces have 

 been reported hitherto from the Shawangunk quartzite. Some- 

 where traces might have been left. I shall look for better ma- 

 terial and more of it, to see if I cannot give this thing a name. 

 Or, as Dr. Seward thinks, is there reason to doubt the algal 

 origin of Cryptozoon? The likeness of the perfectly regular rings 

 in the Shawangunk grit and in the Mohawk Valley limestone 

 is certainly suggestive of regular deposition of lime or silica 

 about a growing circular thallus of some large marine alga. 



Hollis, Long Island, N. Y. 



