Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
I, 
12. 
g 18h 
14, 
15. 
16. 
17. 
18, 
19. 
20. 
SPIRIFER MUCRONATUS, Conrad. 
A specimen of the usual form and proportions. 
Hamilton group. Canandaigua Lake, N. Y. 
An internal cast of a pedicle-valve with greatly extended and acumin- 
nate cardinal extremities. 
Hamilton group. Schoharie county, N. Y. 
An enlargement of a portion of the brachial valve; showing the car- 
dinal process, dental sockets and muscular scars. In this figure the 
lettering is inaccurate; ¢ should be b; the lines @ and r are incor- 
rect; they should be @ and a’ and be directed to the anterior and 
posterior adductor impressions respectively. 
The corresponding parts of the pedicle-valve similarly enlarged. 
Hamilton shales. Western New York. 
A small pedicle-valve with highly extended cardinal extremities. 
Marcellus shales. Near Alden, N. Y. 
An individual with long, narrow, acuminate cardinal extremities. 
Hamilton shales. Darien Center, N. Y. 
SPIRIFER SUBMUCRONATUS, Hall. 
The exterior of a normal example retaining the deltarium, 
An enlargement of the cardinal portion of the same specimen. 
Oriskany sandstone. Cumberland, Maryland. 
SPIRIFER CuMBERLANDIA, Hall. 
An average individual retaining the deltarium and showing the 
lamellose surface. 
Oriskany sandstone. Cumberland, Maryland. 
SPIRIFER BIMESIALIS, Hall. 
Dorsal view of a characteristic specimen. 
Upper Devonian. Independence, Iowa. 
201 
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