Page:A Treatise on Geology, volume 1.djvu/189

 CHAP. VI.



The molluscous reliquiæ are numerous; 326 species being described in the 'Geology of Yorkshire,' without noticing about a dozen others from the coal formation, which are included in the following general summary:

Of these, only about 10 can by any means be considered as of freshwater, or even estuary, origin: and these all belong to the coal formation (unio, anodon, &c.). Many of the genera are the same as those now