272 



Report of the State Geologist. 



Genus Productella, Hall. 



102. Productella navicella, Hall. 



1867, Hall, Pal. N. Y., vol. 4, p. 156, pi. 23. 



This species is rare and has been found only in the Encrinal limestone. 

 The specimens are small, with the shell partly exfoliated, but show the spine 

 bases, which are more pronounced on the front of the shell. 



103. Productella spinulicosta, Hall. 



1867, Hall, Pal. N. Y., vol. 4, p. 160, pi. 23. 



This is the common form of productoid shell in the Hamilton group of 

 this region. , It occurs in all stages of preservation, usually, however, more or 

 less crushed. It has been observed in most of the beds of the Lower shale, 

 down to the Strophalosia bed, and is occasionally abundant. It is rare in the 

 Encrinal limestone and has not been observed in the lower Moscow shales. 

 In the upper Moscow shales it occurs two to three feet below the Styliola 

 band, at Section F. Near the lower end of this section the strata are thrown 

 into a slight anticlinal fold of small extent, and it is there that the specimens 

 occur. They are all very badly crushed, but preserve the characteristic spine 

 bases. Numerous slender elongated and curved spines occur, most of which 

 are detached from the shell and lie scattered on the rock surface. The 

 specimens figured by Hall on PI. 23, fig. 34, Pal. N. Y. vol. 4, probably came 

 from this locality. 



Genus Strophalosia, King. 

 104. Strophalosia trujstcata, Hall. 

 1867, Hall, Pal. N. Y., vol. 4, p. 160, pi. 23. 

 1892, J. Hall and J. M. Clarke, PaL N. Y., vol. 8, pt. 1, p. 314, pi. 15B, 17. 



I have not found this species at Eighteen-mile creek, but on the lake 

 shore at Hamburgh-on-the-lake it occurs in great numbers in a thin band of 

 limestone, the Strophalosia bed, to which it is practically restricted. A single 

 specimen was found in the Nautilus bed just overlying. It likewise occurs 

 in the Marcelius shales. 



