162 
INOCERAMUS vetustus. 
TAB. DLXXXI 2. 
Spec, Char. Ovate,, convex, smooth, regularly un- 
dulated ; valves nearly equal ; beaks short, 
pointed, curved ; a concave space in the ante- 
rior side resembling a 
line short. 
Very regularly arched and gradually rising undula- 
tions of a smooth surface distinguish this from I. Bron- 
gniarti, independently of the difference in the anterior 
side. I have not seen the hinge, but the line to which 
it is attached is short ; the front is very round. 
Occurs in the Mountain Limestone at Castleton in 
Derbyshire, and near Settle in Yorkshire. 
INOCERAMUS dubius. 
TAB. DLXXXIV.— /g. S. 
Spec. Char. Ovate pointed, concentrically striated 
and indistinctly waved ; valves unequal, both 
convex ; beaks short, pointed. 
Strongly resembling I. concentricus. The convexity 
of the valves is variable ; one valve is sometimes flat : 
it is then more strongly marked by the striae formed of 
the edges of the laminae, so characteristic of shells of the 
genus Inoceramus. I have not seen the hinge. 
A mass of indurated Alum Shale, containing brilliant 
casts in Pyrites of this shell and a portion of Ammo- 
nites elegans ? was collected by that indefatigable geo- 
logist, R. I. Murchison, Esq. on the Whitby coast in 
1826. A portion of it is the subject of this figure. 
large lunette ; hinge 
