PLATE 28. 
Legend: A. Delthyrium. C. Dental sockets. 
t. Teeth. c’. Crural bases. 
S’. Apical callosity. r. Diductor scars. 
D. Deltarium. a. Anterior adductors. 
D. Delthyrial groove. a’, Posterior adductors. 
F. Delthyrium. a.’, a." (Pedicle-valve) anterior and 
d. Dental plates. posterior divisions of the 
j. Cardinal process. cardinal area. 
SPIRIFER, Sowxrsy. 
(OstroLatt.) 
Page 757. 
~ 
SpPIRIFER AUDACULUS, Conrad. 
Fig. 1. The interior of a pedicle-valve; showing the muscular area and 
delthyrial callous. 
Figs. 2, 3. Dorsal and profile views of the exterior. 
Fig. 4. The interior of a brachial valve; showing the articulating apparatus 
and adductor scars. 
Fig. 5. The median portion of the cardinal area of the pedicle-valve, en- i 
larged; showing the external form and extent of the delthyrial 2 
callous. 
Fig. 6. Asimilar portion of the pedicle-valve, enlarged to show the apical 
callous and the lower part of the deltarium. 
Fig. 7. An enlargement of a portion of the interior of the brachial valve ; 
showing the adductor impressions and the articulating apparatus, 
Hamilton shales. Western New York. 
SPIRIFER MACRONOTUS, Hall. 
Fig. 8. A cardinal view of a large example retaining the deltarium. 
Hamilton shales. Western New York. : 
SPIRIFER ASPER, Hall. 
_ Fig. 9. Front view of a normal individual. 
Hamilton group. New Buffalo, Iowa. 
Fig. 10. Cardinal view of a pedicle-valve with highly developed delthyrial 
callosity. 
Hamilton group. Rockford, Iowa. 
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