274 C. SCHUCHERT — LOWER IIELDERBERG-ORISK ANY FORMATIONS 



11 Below the oolitic limestone there are about 30 feet of shale which in turn rests 

 upon Ordovician limestone." 



Other Helderbergian areas are described by Dana as follows: 



" The Saint Lawrence tidal waters of this period must have extended westward to 

 the border of Vermont and Montreal and southward along the Connecticut valley. 

 In Canada, in the line of the Connecticut valley, Lower Helderberg fossils occur in 

 Dudswell and near lake Massawipi and Aylmer. They are also found in northern 

 New Brunswick, northern Maine, near Square lake, and along the Gaspe-AVorcester 

 trough. They also occur in southern New Brunswick and near the coast in Pem- 

 broke, Maine, with many fossils, and in northern Nova Scotia, within the limits of 

 the Acadian trough."* 



A typical Helderbergian fauna is also known from Kennedy channel, 

 latitude 80°-81° north, longitude 70° west. Doctor Hayes here collected 

 the following species identified by Meek : f 



Zaphrentis hayesii Meek. Anoplbtheca concava (Hall). 



Syringopora sp. undet. SpiHfer perlamellosus Hall. 



Favosites sp. undet. Loxonema (f) kanei Meek. 



Leptsena rhomboidalis (Wilckens). Orthoceras. 



Strophonella headleyana Hall? lllsenus. 

 Stropheodonta beckii Hall? 

 Jilt ynchonella sp. undet. 



HELDERBERGIAN FAUNA 



Relation to the Siluric. — From the appended list of the species of this 

 fauna and their distribution, it is seen that no less than 426 are described, 

 with 33 undescribed, in the Beecher collection. Sixteen of these, err 

 about 3] per cent, come from the Niagaran and Manlius formations. If 

 the individual species are examined, it is seen that 5 have no particular 

 stratigraphic value: Favosites gotlandicus Billings is probably a lax iden- 

 tification ; Halysites catenularia is also known in the Trenton and Niagara ; 

 Leptsena rhomboidalis exists from the Trenton through nearly all the in- 

 termediate horizons into the base of the Lower Carbonic; Orthothetcs 

 subplanus belongs to a genus having no particular significance excepting 

 its post-Ordovicic development, and Alrypa reticularis begins near the base 

 of the Siluric, and is continuous throughout the Devonic. If the doubt- 

 ful species and those not characteristic of the Siluric are eliminated, as 

 Favosites gotlandicus, Halysites catenularia, Atrypa reticularis, and Leptsena 

 rhomboidalis, the Helderbergian will be found to derive but 10 forms in 

 its fauna of 459 species from the Siluric; i. e., 3 from the Niagaran and 

 8 from the Manlius. This is a little more than 2 per cent. 



* Dana : Manual of Geology, 4th ed., 1896, p. 658. 



f-Amer. .lour. S<-i., 1865, p. 31. The specimens are in the V. s. National Museum. 



