260 " NEW YORK STATE MUSEUM 



shows 12 annulations which are angular with sharp crests. The 

 vertical distance from furrow to ridge is about .5mm; from crest to 

 crest of the annulations is 3.2mni. The concavity of the septum is 

 one third of its width. No finer surface characters are preserved 

 if they ever existed. 



TRILOBITA 



Proetus protuberans Hall 



One well preserved pygidium with the characteristic flattened 

 marginal border was found in the Coeymans. 



Phacops logani Hall 

 Several specimens found in the Coeymans and New Scotland. 



P. pipa Hall and Clarke 

 Several specimens found in the Onondaga. 



Dalmanites cf. anchiops (Green) 



A portion of a cephalon of what appears to be this species was 

 found in the lower Onondaga. 



D. dentatus Barrett 



Exceedingly abundant in the >4 foot Trilobite bed, also rarely 

 found through the entire 30 feet of the Lower Oriskany. An indi- 

 vidual of average size measured: pygidium, 30mm by 28mm; 

 cephalon, 30mm by 35mm in length and breadth respectively. The 

 pygidium arched 11 mm and had a spine at its end 4mm long. 



D. pleuroptyx (Green) 



Represented by one pygidium from the Favosites bed and another 

 from the Coeymans, proper. 



Homalonotus vanuxemi Hall 

 Very abundant in the lower Oriskany, specially in the Trilobite 

 bed. A pygidium of average size measured 35mm in length by 

 37mm in breadth at its widest portion and arched from 4mm to 5mm. 



ADDENDUM 



We are indebted to Dr S. T. Barrett of Port Jervis N. Y., an active 

 local geologist, for the opportunity of noting the two succeeding 

 species from the Oriskany of Trilobite mountain. 



