TRENTON CONGLOMERATE OF RYSEDORPH HILL 71 



consin and Minnesota ; it has also been found in the Black river 

 beds of the Poland limekiln section by White^ and in the Moshier 

 quarry, near Newport, by Prosser and Cuniings;^ and in the 

 Trenton of Canada and New York, where the last named inves- 

 tigators found it^ in the upper third of the limestone section at 

 Trenton Falls, and ;n the limestone of Tribeshill, and Patterson- 

 ville in the Mohawk valley. (Group 7) 



Leperditia resplendens sp. nov. 

 PI. 5, fig. 21-27 



Valves subrectangular, hinge line straight, cardinal angles 

 drawn out into mucros, anterior and posterior ends subparallel, 

 the anterior slightly truncate, ventral margin little curved, sub- 

 parallel to the dorsal line, ventral angles uniformly rounded. 



Surface forming an inclined plane, beginning near the ventral 

 nuargin and eloping sometimes with a slight convexity or con- 

 <^avity to the hinge line, ventral slope abrupt, vertical, or even 

 slightly overhanging. Surface when well preserved strongly 

 glossy, in oblique light, however, exhibiting a very shallow pitting 

 as of internal pores shining through the surface layer. Eye 

 tubercles distinct in a shallow nuchal furrow. Muscle spot often 

 externally indicated as a round shallow pit. 



Most specimens show a very pretty, regular, pitting over the 

 ventral part, separated by an irregularly jagged outline from the 

 smooth glossy part, which lies higher than the pitted part of the 

 shell. Other valves show only scattered fragments of the 

 apparently smooth surface layer over the pitted part of the valve 

 and there are other specimens where the entire surface is pitted. 

 In those forms where the surface cuticle is somewhat less 

 exfoliated, the position of the muscle spot is indicated by a more 

 or less asteroidal fragment of the smooth layer preserved above 

 the pitted parts. 



A deep furrow passes from near the cardinal angles around the 



1 Trans. N. Y. acad. scl. 1896. 15:83. 



2 N. Y. state geol. 15th an. rep't. 1898. 1 ::631. 



3 N. Y. state geol. 15th an. rep't. 1898. 1:625. 



