PLATE 33. 
Legend: pl. Shoe-lifter process. dl. Dental plates. 
Figs. 1, 
Fig. 3. 
Fig. 4. 
Fig. 5 
Fig. 6 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Fig. 11. 
Figs. 12 
Fig. 14. 
s. Septum (pedicle-valve). d. Spondylium. 
s'. Septum (brachial valve). 
MERISTINA, Hatt. 
Page 770. 
Meristina Marta, Hall. 
2, Dorsal and profile views of an average adult. 
The cardinal portion of a mature pedicle-valve; showing the open 
delthyrium and the thickened teeth supported by dental plates. x 2. 
The cardinal portion of the brachial valve; showing the median cleft 
in the hinge-plate, forming an elongate cavity supported by a median 
septum. X 2. / 
Niagara group. Waldron, Indiana. 
. An internal cast of a pedicle-valve; showing the impression of the 
muscular area and vascular sinuses. 
Niagara dolomites. Bridgeport, Illinois. 
. A preparation showing the structure of the brachidium. 
Lateral view of one of the spiral cones in its normal relations to the 
valves. 
Niagara group. Waldron, Indiana. 
MERISTA, Svzss. 
Page 771. 
Merista TEnnessrensis, Hall. 
Dorsal view of a broad individual, 
Ventral view showing the cavity left by the removal of the ‘‘ shoe- 
lifter” process. 
The interior of a brachial valve; showing the divided hinge-plate and 
median septum. 
The interior of a pedicle-valve. 
Lower Helderberg group. Perry county, Tennessee. 
Merista Typa, Hall. 
, 18. Dorsal and profile views of a normal adult. 
The interior of a pedicle-valve; showing the great width of the 
“‘shoe-lifter”” and the extension of the dental plates upon its 
surface. 
218 
