PLATE 26. 
Legend: d. Dental plates. a. Anterior adductors. 
j. Cardinal process. a. Posterior adductors. 
b. Dental sockets. r. Diductors. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
8. Median ridge. 
SPIRIFER, Sowsrsy. 
(APERTURATI.) 
Page 756. 
SPIRIFER ARENOsuS, Conrad. 
1. Dorsal view of a small but characteristic example. 
. A preparation showing the structure of the brachial supports. 
Oriskany sandstone. Cumberland, Maryland. 
Sprrirer Wairneyi, Hall. 
. Dorsal view of a normal example. 
. The interior of a brachial valve ; showing the articulating apparatus 
and muscular scars. 
Upper Devonian. Rockford, Iowa. 
SPIRIFER DISsJUNCTUS, Sowerby. 
. An internal cast of an example with extended cardinal extremities; 
showing the scar of the diductor muscle. 
Chemung group. Southern New York. 
SprrireR Honexrrrornt, Hall. 
. Dorsal view of the exterior; showing the fine plication and obscure’ 
median fold. 
Upper Devonian. Rockford, Iowa. 
SPIRIFER OAMERATUS, Morton. 
. Dorsal view of a large individual; showing the usual angular fascicu- 
lation of the plications. 
Coal measures. Missouri. 
. An enlargement of a portion of the internal cast of the brachial valve 
showing the subdivision of the narrow muscular area into anterior 
and posterior adductor scars. 
Coal measures. Tilinois. 
204. 
