PLATE 59. 
.1-11. AMPHIGENIA ELONGATA. 
1. Dorsal valve of a specimen of medium size. 
2. Dorsal view of another individual of a more regularly elliptical form, showing a strongly 
striated surface. 
3. Ventral'side of a much elongated specimen preserving the shell on the upper part. 
4-6. Profile, dorsal and cardinal views of a specimen of medium size and form. 
7. Interior of an imperfect dorsal valve, showing the hinge-plate, dental sockets, vascular lines, etc. 
c c, points for the attachment of the crura; /, foramen which passes beneath the hinge 
plate and opens between the septa; s s, the double septum bordering the adductor mus¬ 
cular scar. 
8. Dorsal view of a partial cast, showing muscular impressions and vascular lines, the cavity 
left by the removal of the hinge plate and at /, the filling of the foramen which passes 
from the beak beneath the hinge plate. 
9 Cast of a large dorsal valve, showing the muscular impressions and the cavity left by the 
removal of the hinge plate, the filling of the foramen, etc. 
10. Longitudinal section of a specimen, showing the septa and processes of both valves : a, the 
thickened shell of the dorsal valve; c, the crura with its expansion to form the loop; d s, 
dorsal septum; s, ventral septum; x, one of the dental lamellae which unite on the sep¬ 
tum to form the spoon-shaped process of the ventral valve. 
11. Cardinal view of a large cast of both valves;/, the filling of the foramen of the dorsal 
valve, showing its connection with the interior; s, the cavity left by the removal of the 
septum; x, the filling of the inside of the spoon-shaped process. 
