Legend : 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 7. 
. The interior of a brachial valve; showing the articulating apparatus. 
PLATE 24. 
D. Deltarium. c. Crural bases. 
F. Foramen. s’. Callosity in rostral cavity. 
t. Teeth. j. Cardinal process. 
s. Septum. a. Adductor scars. 
A. Cardinal area. r. Diductor scars. 
b. Dental sockets. 
SPIRIFER, Sowzrsy. 
(LaMELLOSI.) 
Page 754. 
SPIRIFER MESACOSTALIS, Hall. 
. An internal cast of the pedicle-valve ; showing the cavity of the 
median septum and dental plates. 
Chemung group. Southern New York. 
SPIRIFER RARICOsTUS, Conrad. 
An oblique view of the pedicle-valve ; showing the median septum. 
Dorsal view of an essentially entire individual. 
Corniferous limestone. Western New York. _ 
SPIRIFER SULCATUS, Hisinger. 
An enlargement of the central portion of the cardinal area of the 
pedicle-valve’; showing the discrete deltidial plates. 
An individual of normal proportions ; showing the lamellose exterior. 
Niagara group. Lockport, N. Y. 
SPIRIFER PERLAMELLOSUS, Hall. ; ” 
The interior of a pedicle-valve ; showing the imperforate deltarium 
and the median septum. 
A normal adult shell, retaining the deltarium and foramen. 
Lower Helderberg group. The Helderbergs, N. Y. 
Sprrirer varicosus, Hall. 
x2. 
. A brachial valve ; showing the character of the exterior. 
. An enlarged view of the central cardinal region of the pedicle-valve. 
Corniferous limestone. Western New York. 
200 
