CARBOMFEROUS FRESH WATER LIFE. 87 



call for special mention, ami each is worthy of still further in\estijiatiou: 

 First, the occurrence near the base of the limestone of a fresh-water fauna; 

 second, the v.uned. development of the Lamellihnmchiaies, a class which has 

 heretofore been but spariug-ly represented in the collection of Carboniferous 

 fossils from the Cordillera ; third, the minf>-lin<>- near the base of the horizon 

 of Devonian, Lower Carboniferous and Coal-measure species in gray lime- 

 stone directly overlying beds characterized by a purely Coal-measiu'e fauna. 



Fresh-water Life.— The lowcst Strata from wliicli we have any record of 

 organic life from this epoch are found at the extreme northeast corner of New 

 York Mountain, and also near the railway cut immediately south of the 

 Richmond furnaces. Both localities lie just east of the Hoosac f;iult, which 

 brings up Carboniferous beds against the Silurian. But for the alluvial 

 deposits, which occupy the valley, tlie beds of tlu^ two localities would 

 ])robably be found to be continuous; the rocks in both are similar. There 

 occur here 100 feet or more of fine claj's and grits, interstratified with 

 arenaceous and argillaceous limestones passing up into pure limestone, 

 showing abrupt changes and rapid deposition. In these transition beds 

 were found abundant evidence of a varied fresh-water life, it being possi- 

 ble to determine several distinct species. The shells indicate a shallow 

 water tauna, as is also clearly established bv the mode of deposition of the 

 sediments. Mingled with these shells are a few fragmentary bits of twigs 

 and stems of plant life, for the most part referable to a coniferous growth, 

 and showing signs of ha\ang been washed down from a land surface that 

 could not have been very far away. Mr. Walcott has briefl}- described 

 three species: one belonging to the genus Physa, named by him P. prism; 

 another form is a pulmonate shell, allied to the genus Auricula, and to 

 which he has given the name Zaptijchius carhonariii; a third shell is related 

 to, if not identical with, AinpuUaria, and is provisionally nametl after the 

 Director of the Geological Survey, A. poivcUi. The discovery of fresh or 

 brackish water shells so low down in the Paleozoic and so remote from any 

 known locality of similar beds renders their mode of occurrence one of 

 peculiar interest. 



Lameiiibranchiate Fauna.— p^'om the hoi'izou of the Lower Coal-measm'es 

 there have been collected over forty species of Lameiiibranchiate shells, a 



