EXPLANATION OF PLATES 223 



Lunulicardium fragile Hall 

 p. 168 



Fig. 



18 A large left valve with an unusually broad anterior expansion. 



x3 



19 A similar specimen from the lower shale beds, x 3 



Onychochilus ( ?) nitidulus Clarke ? 

 p. 170 



20 A small exfoliated specimen, x 10 



Ambocoelia nana Grabau 

 p. 165 



21-23 Ventral, lateral and dorsal views showing the spinous sur- 

 face, transverse form! and small size compared with A. 

 s p i n o s a Clarke, x 3 

 All specimens are from the Stafford limestone of Lancaster 

 N. Y. unless otherwise indicated. 



