19 7 
TRIGONIA clayellata. 
TAR. LXXXYII . — Upper figure. 
Spec. Char. Triangular, rather wider than long% 
with ten or more oblique rows of tubercles; 
anterior side straight, with three longitudinal 
knotted ridges. 
Syn. Curvirostra rugosa clavellafa major. Laid. 
Lithoph. p. 36 . T. 9 . F. 700 . 
Trigonia clayellata. Park. Org. Rem 3. T. 12 . F. 3 . 
1 he posterior side and angle are rounded ; anterior side 
straight, slightly gaping near the hinge, and forming an 
acute angle with the front: there are about ten rounded 
tubercles perfectly distinct in each row. 
I have figured this from a specimen sent me by the Rev* 
S. Rackett from Radipole near Weymouth; such is also 
found at Portland. The shell is preserved of much the 
same texture as a recent oyster shell which has laid in a 
blackening mud. The same species has been found in 
Oxfordshire by Mr. W. Walter, and I have a cast in 
Sandstone, from Gunton in Suffolk, that appears to be the 
same species, but its length and breadth are more equal, 
and it is larger. I have also received, by favor of Alex- 
ander M’Leay, Esq. numerous specimens of a species much 
resembling this from Boulogne; they are from one to five 
inches wide, much wider than long, and can hardly be 
called triangular, the anterior side is drawn out to a greater 
length, and the depth is also greater: they are much worn, 
with oyster-shells sometimes adhering to them : the earth 
about them is a marly clay. 
The lower figures represent a shell which so nearly resem- 
bles the larger one, that I can only consider it as a variety ; 
in it a few of the tubercles in each row are united, so as to 
form interrupted ridges. I thought it a convenient addition 
to the plate, although the specimen was not very perfect, 
as it shows the hinge, which the compactness of the stone 
in the upper specimen prevents the display of. This is 
from the inferior Oolite at Little Sudbury, by favor of the 
Rev. H. Steinhauer. 
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