12 NEW YORK STATE MUSEUM 



mens and other valuable aid rendered in the prosecution of these studies, 

 the writer is under great obligations to Dr John M. Clarke. Other material 

 has been freely placed at his disposal by Mr Charles Schuchert, of the Pea- 

 body Museum at Yale University, by Professor Bashford Dean, of Columbia 

 University, and by the authorities of the American Museum of Natural 

 History in New York. The illustrations, both for plates and text figures, 

 have been provided by the Museum of Comparative Zoology at Harvard 

 College, Cambridge, Mass., and the New York State Museum. 



CONSPECTUS OF SPECIES ARRANGED ACCORDING TO 

 THEIR GEOLOGICAL OCCURRENCE 



CHAMPLAINIC 

 Class AGNATHA 



Astraspis desiderata Walcott. Lower Siluric of Canyon City, Col. 

 ? Dictyorhabdus priscus Walcott. Lower Siluric of Canyon City, Col. 

 ? Eriptychius americanus JValcott. Lower Siluric of Canyon Cit)', Col. 



SILURIC 

 Class AGNATHA 



Cyathaspis acadica Alatthczv. From strata of supposed Niagara age in 



Kings county. New Brunswick. 

 Palaeaspis americana Claypolc. Bloomfield sandstone ; middle portion of 



the Salina beds. Perry county, Pennsylvania. 

 Class PISCES 

 Onchus clintoni Claypole. Clinton beds (Lower Niagaran); Pennsylvania. 

 Onchus pennsylvanicus Claypole. Bloomfield sandstone ; middle member 



of the Salina beds, Perry county, Pennsylvania. 

 Onchus sp. Niagara beds of Cumberland, Maryland. 



LOWER DEVONIC 

 Maine-New Brunswick province 



Class AGNATHA 



Cephalaspis campbelltonensis Whiteavcs. Lower Devonic; Campbellton, 

 N. B. 



