112 ROYAL SOCIETY OF CANADA 
DESCRIPTION OF THE PLATE. 
Fig. 1. Obolus torrentis. Dorsal valve, Mag. 3. Coldbrook terrane. 
Fig. 2. Obolus triparilis—a, Ventral valve—b, Dorsal valve, interior—c, Sec- 
tion of same. All mag. +. Lower Etcheminian. 
Fig. 3. Obolus discus—a, Ventral valve—b, Dorsal valve—c, Interior of same. 
All mag. 4—d, Cardinal area of dorsal, further enlarged. Lower Etcheminian. 
Fig. 4. Obolus œquiputeis—a, Ventral valve—b, Interior of same—c, Dorsal 
valve—d, Interior of same. All mag. $ —e, Surface markings, enlarged f 
Lower Etcheminian. 
Fig. 5. Obolus Bretonensis—a, Ventral valve—b, Interior of same—c, Section 
of same—d, Dorsal valve—e, Interior of same. All mag. ?. Upper Etche- 
minian. 
Fig. 6. Obolus lens—a, Ventral valve—b, Interior of same—c, Section of 
same. All mag. 21 —d, Dorsal valve—e, Interior of same. Both mag. ? Upper 
Etcheminian. 
Fig. 7. Obolus pulcher—a, Ventral valve, outline of interior—b, Dorsal valve, 
interior. Both mag. + Protolenus Fauna. | 
Fig. 8. Obolus pristinus—a, Ventral valve—b, Side of same—c, Mould of a 
ventral (?)—d, Back view of same. All mag, 2—e, Dorsal valve, young, mould 
of. Mag. +. Protolenus Fauna. 
Fig. 9. Obolus Ella—a, Ventral, outline of interior—b, Dorsal valve, outline 
of interior. Both mag. 2. Peltura Fauna. 
Fig. 10. Obolus Apollonis. Eichwald, var. Quenstedti. After Michwitz. Dia- 
grams of the ventral and dorsal valves, enlarged; showing positions of the 
muscle scars and vascular trunks (the branches of the latter are omitted). 
Dictyonema Fauna, or below. 
Fig. 11. Obolus refulgens—a, Ventral valve, interior—b, Dorsal valve, mould 
of interior. Both mag. #. Dictyonema Fauna. 
Fig. 12. Metoptoma Amii, n. sp.—a, Shell seen from above—b, Same from the 
side. Both mag. ?. Peltura Fauna of Mt. Stephen, Field, B.C. 
