81 
ORTHOCERA gygantea, 
TAB. CCXLVI. 
Spec. Cuar. Shell gradually tapering, smooth, or 
striated ; aperture oval, with the two diameters 
in the proportion of 7 to 8, siphuncle at a 
small distance from the centre, septa direct, 
numerous, deep. 
———— 
Tue aperture is eight or more inches in diameter, and 
as the shell diminishes at the rate of about one inch in a 
foot, its length may often exceed eight feet. The 
broader extremity is slightly expanded, and probably the 
other does not taper so rapidly as the middle, hence the 
above length may be under-rated. The thickness of the 
shell is about one fourth of an inch. On one small spe- 
cimen the surface is finely striated longitudinally in the 
same way as O. striata (tab. 58) from which however it 
differs in not being compressed, and the siphuncle not 
being in the centre. The shell is so incorporated with 
the stone that it is difficult to discover the outer surface 
and consequently whether it be striated all over or only 
towards the smaller end. 
This species of Orthocera does not agree with any of 
those described by Dr, Fleming*, or any other writer I 
have met with, but in general the descriptions are not 
particular enough for the discrimination of species, when 
more than one such are nearly allied. Had not the 
“¢ Orthoceratites superficie levi’ of the Rev. Mr. Uret 
been referred to by Dr. Fleming, under his O. levis, 
which differs from O. gigantea, in the position of the 
———— nas 
* See “ Annals of Phil.’ V. 199. 
+ History of Rutherglen and East Kilbride,” p. 306, t. XVI. f. 3. 
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