lOO NEW YORK STATE MUSEUM 



entirely inclosed by the limestone, from which they are differen- 

 tiated by their structureless character. The lenses exposed on the 

 Rome, Watertown and Ogdensburg road are rich in shells of 

 orthoceratites and shields of trilobites (Illaenus ioxus), 

 while the lens in the gorge yields chiefly brachiopods, the most 

 abundant of which are the smooth Whitfieldellas, the small, W. 

 n i t i d a and the larger W. o b 1 a t a being the most common. 



The following species have been obtained from the lens in the 

 gorge: 



Brachiopoda 



1 Whitfieldella nitida abundant 



2 W. n i t i d a o b 1 a t a abundant 



3 W. i n t e r m e d i a common 



4 A try pa reticularis; specimens with strong, rounded 



bifurcating striae, noded at intervals by strong concentric 

 striae, and apparently intermediate between the typical form 

 of the species as it occurs in the Clinton and upper lime- 

 stone and A. nodostriata, the most abundant form 

 of the Rochester shales. 



5Atrypa nodostriata; rather common, convex and 

 more elongate than in the shale above, with the plications 

 generally sharper and bifurcating near the front. The 

 pedicle valve has a distinct sinus bordered by strong plica- 

 tions, the corresponding fold being marked merely by 

 strong plications. Anterior margin distinctly sinuate. The 

 nodulations are not well preserved except in specimens from 

 the shaly portions. 



6Atrypa rugosa; several small specimens, both valves 

 very convex, with strongly defined sinus in pedicle valve, in 

 the center of which is a small plication. Plications bifur- 

 cate and also increase by intercalation; crossed by strong 

 rugose lines. 



7 Rhynchotreta cuneata americana rare 



8 Camarotoechia neglecta rare 

 QAnastrophiainterplicata rare 



10 Spirifer niagarensis; common, large and robust, 

 with long hinge line and moderately high area, and strongly 

 incurved beak. The sinus is flanked by two stronger plica- 

 tions and extends to the beak. The plications are flattened 

 on top. 



