Legend: 
PLATE 51. 
c. Crural bases. a, Anterior adductor scars. 
a. Posterior adductor scars. 
Suscenus BEACHIA, Hatt. 
Page 850. 
Bracuta Surssana, Hall. 
Figs. 1, 2, 3. Ventral, profile and dorsal views of a typical example; showing 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
the outline, contour and plication of the valves and their lateral 
marginal inflexion. 
. Front view of conjoined valves; showing the fine plication of the 
surface and the inflexion of the lateral margins. 
5. View of the hinge-plate. X 2. 
6. The interior of a brachial valve; showing the hinge-plate, medially 
10. 
11. 
depressed and perforated at its apex by the visceral foramen, the 
dental sockets, and the form of the loop with the median rod-like 
process extending backward and upward from the anterior plate. 
- Median longitudinal section of conjoined valves; showing in profile 
the loop with its long, erect crural apophyses, the elevation and 
direction of the median process extending backward from the 
anterior plate. 
Oriskany sandstone. Cumberland, Maryland. 
MEGALANTERIS, Suzss. 
Page 859. 
MEGALANTERIS OVALS, Hall. 
. An internal cast of the pedicle-valve; showing the filling of the deep 
scar of the diductor muscles, enclosing the small subcordate adductor 
scar, with traces of vascular sinuses and genital markings. 
. A similar view of another specimen to which a portion of the pedicle- 
valve adheres; showing the cavity of the hinge-plate and the division 
of the muscular area into anterior and posterior scars. 
The dorsal side of an internal cast; showing the deep impression of 
the prominent hinge-plate and cardinal process, and the adductor 
muscular scars. 
Oriskany sandstone. Schoharie, N. Y. 
Interior view of the cardinal portion of the brachial valve enlarged; 
showing the hinge-plate and the stout, erect, bilobed, and deeply 
grooved cardinal process; the broad crural bases and a portion of 
the muscular impression. 2. 
Oriskany sandstone. Albany county, N. Y. 
260 
