Silurian and Devonian Fossils of Canada. 441 



a prominent obtusely angular canina ; surface marked with fine 

 concentric strise. Width eight lines ; length four lines. 



Locality and Formation. — Blue Point, Lake St. Johns ; Trenton 

 limestone. 



Collectors — J. Richardson, R. Bell. 



Genus Obolus (Eichwald). 

 . Obolus Canadensis (Billings). 



Fig. 19. 



Fig. 20. 



Fig. 21. 



Fig. 22. 



Fig. 23. 



Figure 19. Dorsal valve. 



20. Interior of dorsal valve. 



21. Dorsal view of an elongated specimen which has both 



valves in place but a little distorted. 



22. Side view of the same specimen. 



23. Ventral view. 



Description. — The form of this magnificent species is somewhat 

 variable, the width being often greater than the length, and some- 



