Mr. J. Lycett on the genus Quenstedtia. 137 



aggregate of these characters, it must be admitted, fully justifies 

 the separation of Quenstedtia from Psammobia; and it yet remains 

 to be demonstrated that true Psammobia are found in any rocks 

 older than the Tertiary system, none of the so-called .Jurassic 

 Psammobia having hitherto exhibited the characters of that genus 

 free from ambiguity. 



