284 



Report of the State Geologist. 



132. Liorhynchus limitaris, Vanuxem. 



1867, Hall, Pal. N. Y., vol. 4, p. 356, pi. 56. 



This species occurs in the lower eight or ten feet .of the transition shales, 

 and in the upper Marcellus. 



133. Liorhynchus dubius, Hall. 

 1867, Hall, Pal. N. Y., vol. 4, p. 364, pi. 56. 

 At Section 13, at a depth of about twenty feet below the Encrinal lime- 

 stone, two small valves were found which correspond essentially with fig. 22 

 of the above plate. No fold or sinus is indicated in the specimens, and I refer 

 them provisionally to this species, which was originally described from the 

 Marcellus shale. 



Genus Centronella, Billings. 



134. Centronella impressa, Hall. 

 1867, Hall, Pal. N. Y. vol. 4, p. 402, pi. 61a. 



This shell is known to me only from the Encrinal limestone of Eighteen- 

 mile creek, where it occurs in considerable numbers. The specimens are 

 small and the brachial valve usually bears the characteristic central impression 

 for the entire length. About thirty-five specimens were obtained. 



Genus Cryptonella, Hall. 



135. Cryptonella planirostra, Hall. 



1867, Hall, Pal. N. Y., vol. 4, p. 395, pi. 61. 



This is another species which is practically restricted to the Encrinal 

 limestone though several specimens from the shale below have been referred 

 to it. The limestone specimens are usually robust and well developed, though 

 most of them are undersized. The specimens from the upper part of the 

 Hamilton shales are usually in a crushed and imperfect condition, and do not 

 exhibit the characters well. Doubtful specimens were obtained from the 

 Pleurodictyum beds, but these may prove to belong to the next. 



136. Cryptonella rectirostra, Hall. 

 1867, Hall, Pal. N. Y., vol. 4, p. 394, pi. 61. 

 This species is common in the upper Pleurodictyum bed and in the 

 bed just overlying, but has not been observed either above or below 

 these. 



