416 ' MINING INDUSTRY. 



on Babylon Hill may be found Syringopora, Retepora, and Smithia hennahii. 

 On Blue Ridge Pleurotomaria and a small Prodwctus ; the latter, however, are 

 extremely rare. 



The following note, from Professor F. B. Meek, to whom the collection 

 was referred, will be sufficient for the purposes of this chapter : 



" The genus S?nitkia is generally regarded as a Devonian type, while the 

 specimens of that genus in the collection seem to be very closely allied to, if 

 not actually identical specifically with, a well-known European Devonian 

 species. The genus Acemularia is also mainly a Devonian type, only some 

 three or four of the thirteen or fourteen species which occur in the Silurian, 

 being found in the rocks of any other age ; while the single species of this 

 group, contained in the collection, is apparently identical with a well-known 

 European Devonian species. Among the molluscan remains from this rock 

 we have the well-known Atrypa reticularis, which, however, occurs both in 

 the upper Silurian and Devonian, though it is not known to be represented by 

 any of the forms usually referred to it in any part of the Carboniferous series. 

 But here we have it directly associated with a small Productus. This last- 

 mentioned genus, although most abundant in the Carboniferous, likewise 

 occurs in the Devonian, but has not yet been found in the Silurian. So that 

 the association of these two types, in the same beds, again points to the De- 

 vonian. The associated Spirifers are most nearly allied to Devonian species; 

 while scarcely any of the other fossils from this rock can be properly said to 

 point to the Silurian or the Carboniferous." 



The calcareous shale, as already remarked, is entirely non-fossiliferous. 

 The siliceous limestone formation contains large numbers of Crinoid stems. 

 Large masses of chert occur, completely filled with fragmentary remains of 

 Crinoids, in silica, while, in the j3ure limestone, occur the same remains, but of 

 nearly pure white calcite. 



In addition to the Crinoid stems, Productus and Spirifer are found ; of 

 the former a small single valve, and of the latter, molds of a dorsal value in 

 chert. They are not sufficiently well preserved, however, to determine the 

 species definitely. 



The evidences of the age of the argillaceous shales seem to indicate that 

 they belong to the Carboniferous period, although they are not such as to 

 warrant the positive assertion. 



I 



