16 NEW YORK STATE MUSEUM 



black limestone of Rysedorph hill. The specimen is smaller by 

 one half than the average specimens of Ph olid ops 

 trentonensis ; but, it being the only specimen found, 

 a comparison with the variety P h o 1 i d o p s t r e n t o n e n s i s 

 var. minor Winchell and Schuchert, from the base of the 

 Galena limestone at St Paul, is excluded. Judging from the 

 drawing given of that form, the Rysedorph hill specimen shows 

 the same slight truncation as the western form, which becomes 

 more emphasized in Pholidops subtruncatus. 



Hall does not give the exact horizon of his species, which was 

 secured at Middleville, and Dr White and Prof. Prosser did not 

 find the fossil in the sections of Trenton Falls and other locali- 

 ties along the West Canada creek; the western variety occurs 

 in the Black river and lower Trenton beds. (Group 5) 



rafinesquina Hall & Clarke 



Eafinesquina alternata (Emmons) Hall & Clarke 



Leptaena alternata Emmons. Geol. of N. Y. Rep't on 

 second district. 1842. p. 395 



PI. 2, fig. 1 

 Many pebbles of the gray crystalline limestone of Rysedorph 

 hill are filled to the exclusion of other fossils with very large speci- 

 mens of Rafinesquina alternata. The extreme size 

 of a great number of specimens, combined with a remarkable 

 extension of the cardinal region, constitutes a striking variation 

 from the type, which becomes more emphasized in such Lorraine 

 forms as Rafinesquina alternata loxorhytis 

 Meek. Numerous other specimens are remarkable for the 

 strong oblique corrugation of their cardinal regions. Several 

 specimens of great gibbosity and thick shell were also found in 

 the compact reddish gray, ostracode limestone of Rysedorph hill. 

 Rafinesquina alternata is also of frequent occurrence 

 in the matrix of the conglomerate at the Moordener kill and at 

 Schodack Landing. This form ranges from the Chazy to the 

 Lorraine beds and extends from Canada to Minnesota and 

 Manitoba. (Group 7) 



