34 Fossils of the Potsdam Sandstone^- 



Brachiopoda, or arm-footed animals. It comprises about 40 genera,* ancf 

 more than a thousand species, f All of these are extinct, except about 

 seventy species, living in various parts of the existing seas. There arc 

 seven existing species of the genus Lingula known on the coasts of India^ 

 the Philippines, Moluccas, Australia, Feejees, and Sandwich Islands, 

 There are about forty extinct species of the same genus described, and 

 they are distributed through all the formations from the Cambrian up to the 

 surface. 



Two species are mentioned as occurring in the Potsdam sandstone- 

 They are the following : 



Fig 1. Lingula prima. 

 2. Lingula antiqua. 



The first of these, Lingula prima, is about i^the size represented in- 

 Fig. 1. It is of an oval shape, obtuse at both ends, but more broadly 

 rounded at the base than at the beak or upper extremity of the above 

 figure. The surface is marked by faint concentric lines, and by a few 

 concentric wrinkles in some specimens. From the base to the beak it is 

 also marked by fine striae, extending up and down the fossil in that 

 direction. In some cases the latter marks are more distinctly visible than 

 the concentric lines ; but in. others both are equally apparent. 



I^rofessor Hall states that " this fossil is for the most part rare, even 

 in the Potsdam sandstone, though at Keesville, in Essex County, (State of 

 New York) it is abundant, forming distinct laminae in the rock, like films 

 of carbonaceous matter." We are not aware that it has been yet 

 discovered in Canada. 



The next species, Lingula antiqua, is longer than the other and more 

 pointed towards the beak. The base is broadly rounded, and its surface 

 marked by fine concentric lines, but according to Prof. Hall, no longitudi- 

 nal striae are visible. 



Mr. Murray, of the Geological survey of Canada, says that this^ 

 apecies occurs in the Potsdam sandstone, on Lot 22, in the 9th Concession 

 of the Township of Bastard, in the County of Leeds, and also on Lot No. 

 11, in the 11th Concession of the Township of Landsdowue, in the same 



* See Davidson's classification of the Brachiopoda, in the TOliune of the 

 Palaeontographical Society for 1863, page 50. 



f WooJvrard'a Manual of the Moilueca, page 214, 



