204 PALAEONTOLOGY OF NEW JERSEY. 



under the genus Polorfhus (by the two last authors written Polarthus), but 

 I see no evidence from any of the remains whicli I have examined of its 

 generic identity with the Teredo tibialis of Morton, which is the species upon 

 which the genus Polorthus was founded, and I have, therefore, retained it 

 tinder the genus Gastrochcena. 



Formation and localities. — In the Middle Marl Beds at Timber Creek, 

 New Jersey. Mr. Gabb also cites it from the "brown marls" of Burlington 

 County, New Jersey, from which place I have not seen them. 



