PLATE LXXVII. 
(Figures I-il, 23-25 by F. B. Mekk ; 10, 11, 17-22 by G. B. Simpson ; 12-U by K. P. Whitfield ; 26-28 by P. J. Swinton.) 
Subgenus BEACH!A, s.-gen. nov. 
Page 260. 
Beachia Suessana, Plall. 
Fig, 1. The interiors of two pedicle-valves, the upper retaining the deltidial jdates, the lower having 
lost these i lates, but showing the dental lamellse. Both figures show an obscure muscular 
area divided by a low median ridge. 
Fig. 2. The interior of a brachial ’valve ; showing the hinge-plate, medially 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. 
Fig 3. Front view of conjoined ^■alves; showing the tine plication of the surface and the inflexion of the 
lateral margins. 
Fig. 4. 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. 
Fig. 5. Views of the intei-ior of two brachial valves ; showing the inflected lateral mai'gins and some vari¬ 
ation in the condition of the hinge-plate. 
Figs. 6, 7, 9- Ventral, profile and dorsal views of a typical example; showing the outline, contour and 
plication of the valves and their lateral marginal inflexion. 
Fig. 8. Profile of a smaller shell, with the marginal inflexion of the valves extending to the anterior ex¬ 
tremity. 
Figs. 10, 11. Views of the hinge-jdate in two individuals ; showing differences due to age and consequent 
thickening of the parts. X 2. 
Oriskany sandstone. Cumberland, Maryland. 
Genus M EGALANTEBIS, Suess. 
Page 277. 
Megalanteris ovalis, Hall. 
Fig. 12. An internal cast of the pedicle-valve ; showing the Ailing of the deep scar of the diductor muscles, 
enclosing the small subcordate adductor scar, with tiva.ces of vascular sinuses and genital 
markings. 
Fig. 13. The dorsal side of an internal cast; showing the deep impression of the prominent hinge-plate 
and cardinal pi'ocess, and the aiiductor muscular scai’s. 
Fig. 14. A similar view of another specimen to which a portion of the pedicle-valve adheres ; showing the 
cavity of the hinge-plate and the divi.sion of the muscular area into anterior and posterior 
scars. 
Oriskany sandstone. /Schoharie, New York. 
Fig. 15. The ventral side of another internal cast; showing the-impressions of the muscular scars and vas¬ 
cular sinuses. 
Fig. 16. Dorsal view of the same specimen ; slu.-wing the deep cavities left by the grooved cardinal pro¬ 
cess, crui'al bases, and adductor seal’s. 
Figs. 17, 18. Posterior and interior views 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. X 2. 
Figs. 19, 20, 21. Interior, profile and front views of a gutta-percha impression taken from a natural cast of 
the interior, having a very highly developed cardinal process divided on its posterior face by 
a single median groove; showing also the crural bases and muscular area divided by a low 
median septum. 
Fig. 22. The umbonal portion of the brachial valve, drawnjfrom a gutta-percha impression taken from the 
specimen represented in fig. 16. The two grooves on the posterior face of the cardinal process 
are-characterized by series of fine, diverging lines. 
Oriskany sandstone. Albany county. New York. 
