4 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. 74 



The free portion of the flange near the whorl slopes abruptly down- 

 ward, then the flange flattens and gradually assumes an upward 

 curve. In extreme cases the flange may turn backward and become 

 partially inroUed. 



All the known specimens referable to this species come from the 

 massive upper Silurian limestones of Willoughby Island, Glacier 

 Bay, Southeastern Alaska. Collector, Edwin Kirk. 



Cotypes. — The cotypes of Bath'moptei'us liratus are in the collec- 

 tion of the United States National Museum, Xo. 726T1. 



EXPLANATION OF PLATE 



Figs. 1-5. Bafhniopterus liratus, new genus and species. 



1. Vertical median section througli an adult individual. 

 2-5. Various views of an adult individual. Upper Silurian limestone, 

 Willoughby Island, Glacier Bay, Southeastern Alaska. 



o 



