100 NEW YORK STATE MUSEUM 



the more productive fossiliferous beds occur. In part these beds are 

 made up of masses of the lamellibranch Ilionia sinuata, a species 

 described by Hall as Anatina? sinuata, from Herkimer county. 

 It is by far the most abundant of all the species here present. 



Ilionia is a generic type of strong Siluric cast, represented by 

 the well-known and highly characteristic Lucina priscaof Wahlen- 

 berg, from the upper beds on the island of Oesel. Other species are a 

 form of Hormoceras, a strong Siluric type, and a C y r t o c e r a s or 

 Gyroceras making more than one revolution, a small form of Onco- 

 c e r a s , perhaps that identified by Williams asO. ovoides Hall, but 

 which appears to me different in several respects. This genus, O n c o - 

 c e r a s again indicates the Siluric affinity of the fauna. There are 

 species of Orthoceras both smooth and annulated, which have not 

 yet been satisfactorily identified. Among the gastropods are some species 

 of Holopea which are hardly identifiable. Also an Euornphalus, 

 which may be compared with the E. sinuatus Hall of this horizon. 

 Spirifer vanuxemi and Brachyprion varistriatum, which 

 occur throughout the extent of the limestone east and west, are here 

 quite abundant. Also the Atrypa sulcata Vanuxem, which proves 

 to belong to the genus Whitfieldel la, and a large unidentified form 

 of the genus Chonetes. I look on the discovery in this fauna of 

 Halysites catenulatus as of much significance. Though not 

 abundant, the species is thoroughly characteristic. Another coral is 

 present, doubtless that referred to by Prof. Williams as Zaphrentis sp., 

 which I find to have the characters of the new genus Charactophyl- 

 1 u m , and to be most closely allied to the C. (Cyathophyllum)radi- 

 c u 1 u m Rominger, of the Niagaran fauna. A few other species have 

 been observed but not in condition for satisfactory identification. 



It is perfectly clear without farther argument that the types expressed 

 in the foregoing list are very positively indicative of Siluric age, and, 

 furthermore, that they have nothing in common with the true Helderbergian 

 fauna. No single species of the list and none of the generic forms here 

 cited, such as Hormoceras, Oncoceras, Ilionia (or Platy- 

 mermis), Whit f ieldella, Halysites and Charactophyllum, 



