264 



Report of the State Geologist. 



Genus Pholidops, Hall. 



79. Pholidops Hamiltonle, Hall. 

 1867, Hall, Pal. N. Y., vol. 4, p. 32, pi. 3, 



This is a common form, extending through the greater part of the group. 

 The valves have not been found in conjunction, but single valves are common. 

 The internal and external moulds in many cases alone represent these shells. 



The lowest position in which this species has been observed in the Ham- 

 ilton shales, is about forty feet below the Encrinal limestone. It is rare at 

 this level, nor is it very abundant in the next twenty-five feet of the shales. 

 Above this it becomes more frequent until about ten feet below the Encrinal 

 limestone it is a common fossil, occurring both as shells and impressions. 

 Above this it becomes again comparatively infrequent, being only an occa- 

 sional constituent of the faunas for the remainder of the Hamilton shales. 

 No specimens have been found in the Encrinal limestone. In the Moscow 

 shales immediately above, it is quite abundant, but after two or three feet, it 

 becomes rare again, and has not been found anywhere in the upper part of 

 these shales. 



80. Pholidops linguloides, Hall. 

 1867, Hall, Pal. N. Y., vol. 4, p. 414, pi. 3. 



(See also vol. 8, pt. 1, pi. 4i.) 



This species occurs in the Encrinal limestone and in the S. demissa bed. 

 A single separate valve from the limestone allows accurate measurements. 

 Besides this, attached specimens in both shale and limestone were found. In 

 the perfect valve found the beak projects .6 mm. beyond the posterior border 

 of the shell, the total length of the shell being 7 mm., and its width 5.2 mm. 

 The " area " thus formed is arcuate and striated transversely by the lines of 

 growth. A specimen adhering to the interior of a Stropheodonta shows coarse 

 lamellose lines of growth. This specimen measures 7.7 mm. in ante- 

 posterior diameter, and 6.9 mm. in transverse diameter. The shell is much 

 thicker than that of P. Hamiltonice. 



81. Pholidops oblata, Hall. 



1867, Hall, Pal. K Y., vol. 4, p. 414, pi. 3. 



(Also vol. 8, pt. 1, pi. ±i) 



Several specimens of Pholidops from the Encrinal limestone are referred 

 to this species. The specimens are broader at the posterior end, which is 



