I 



THE GEOLOGY OF THE SYRACUSE QUADRANGLE 63 



Among the rarer but highly interesting specimens which occasion- 

 ally reward the collector we may mention spinelike pieces of bone 

 apparently referable to the fish Machaeracanthus and fragments of 

 the giant trilobite Dalmanites (Coronura) myrme- 

 cophorus (Green). 



THE MARCELLUS FAUNAS 



The series of about one hundred feet of strata which have been 

 assigned to the Marcellus formation, exhibit two somewhat diverse 

 faunal elements. These are the Black shale fauna and the fauna of 

 the Agoniatites limestone intercalation which occurs in the lower 

 fifteen feet of the series. 



Though certain species are common to these two lithologic phases 

 of the Marcellus, the limestone is to be distinguished by the presence 

 of large types of cephalopods which are found at no other horizon 

 within the quadrangle. Almost every exposure of this limestone will 

 yield specimens ofGoniatites vanuxerai Hall ( = A g o n - 

 iatites expansus ( Van. ) ) and Orthoceras marcel- 

 lens i s Hall. 



The black shales are prevailingly unfossiliferous, yet thin bands 

 or concretionary masses may present the brachiopod L i o r h y n - 

 chus limitaris ( Vanuxem) and the pteropod S t y 1 i o 1 i n a 

 f i s s u r e 1 1 a (Hall) in countless numbers. Besides these dimin- 

 utive invertebrates the shales occasionally furnish fragmentary re- 

 mains of good sized fishes which can be provisionally assigned to the 

 genera Dinichthys and Onychodus. 



This peculiar association of small bottom-living invertebrates with 

 mobile and planktonic types appears to be a normal one for black 

 shales generally and, taken in connection with the characters of the 

 shales themselves, has been interpreted as signifying an environment 

 similar to that of the present Black sea.^ 



1 Clarke, John M. N. Y. State Mus. Mem. 6, p. 200. 1903. Schuchert, 

 Charles. Geol. Soc. Am. Bui. 20, p. 446. 1910. 



