98 NEW YORK STATE MUSEUM 



account of its great vertical range, will be left out of consid- 

 eration. Also, M o d i o 1 (> |) « i s ef. a v i c u l^o i d e s and 

 Spyroceras cf. anelluts are of little taxouomic value, 

 being poorly represented and not positively identified. 



( ) r t li i s t r i c e n a r i a , T) ;i 1 in a u e 1 1 a t e s t u d i n a - 

 r i a , 1). e u b a e q u a t a var. p e r v e t u s Conrad, P 1 e c t o r - 

 this p 1 i c a t e 1 1 a , D i n o r t h i s p e c t i n e 1 1 a, P r o - 

 t o z y g a e X i g u a , Z y g o s p i r a r e c u r v i r o s t r i s , 

 T. o p h o s p i r a b i c i n c t a , CM a t h r o e p i r a ,8 u b c o n - 

 i c a , T r o h o n e ni a u ni b i 1 i c a t u m , G e r a s a p h e s 

 u 1 r i c h a n a , 111 a e n u s a ni e r i c a n u s , P t e r y g o m e - 

 t o !> u s c a 1 1 i c e p b a 1 u s , G e r a u r u s p 1 e u r e x a n - 

 t li e ni u s and L e p e r d i t i a f a b u 1 i t e s extend partly 

 ill the eastern and partly in the westei-u province, from the Low- 

 ville limestone into or above the Trenton limeetone, and serve, 

 in the detemiinatioii of the age of the pebblee under considera- 

 tion, by a process of elimination, to prove that the fauna to which 

 they belong originated in the Trenton period, and may belong 

 either to the LiKwville, Black river, or Trenton epochs. Paras- 

 t r o i> h i a h e m i p 1 i c a t a ranges from the Black river 

 into the Utica beds, C o n r a d e 1 1 a com p r e s s a from the 

 Black river into Trenton beds, I s o t e 1 u s m a x i m u 6 from 

 the Black river into the Richmond beds. 



Several members of the fauna of the gray limestone pebbles 

 are thus far known only from the oldest epochs of the Trenton 

 period; these are J> o p h o s p i r a p e r a n g u 1 a t a Hall sp. 

 TTall comprised two dilTerent forms under this one si)ecific term; 

 that found in the conglomerate agrees more with the Txjwville 

 limestone type than with the Trenton limestone type. T h a 1 e o p s 

 ovata occurs in the west only in beds of Lowville limestone 

 age, and in Canada in beds in which the Tx)wville and Black river 

 fitages have not been separated. 



I s o c li i 1 i n a a r m a t a var. p y g m a e a is a variety of 

 a species found l.y Walcott in the Black river and Lowville lime- 

 stones, S c h III i d t e 1 1 a c r a s s i m a r g i n a t a var. v e n - 

 t r i I a b i a t a , and K u r y c h i 1 i n a s u b r a d i a t a var. 



