39 
TROCHTJS ornatus. 
TAB. CCXXI.— Fig. l. 
Spec. Char. Conical, depressed, with concentric 
farrows, and diverging striae ; whorls aboye 
depressed, with many tubercular undulations ; 
in the middle flattened, with a longitudinal 
band ; base convex, umbilicated, margin largely 
crenulated. 
A richly ornamented shell : the prominent undulations 
being crossed by rounded furrows, have a knotted ap- 
pearance : the diverging striae are in many parts rather 
obscure ; where they cross the band, they have a semi- 
circular form. Diameter above twice the height. The 
umbilicus appears to be plaited sometimes. 
The inferior Oolite of Dundry has supplied Mr. Braik- 
enridge with the specimens figured. The shells seem to 
have been very thick : their place is occupied by white 
transparent calcareous spar. 
TROCHUS bicarinatus. 
TAB. CCXXI.— Fig. 2. 
Spec. Char. Depressed, conical, with diverging 
striae ; volutions obscurely bicarinated, deeply 
undulated above, concentrically striated be- 
neath ; base convex, umbilicated. 
The cast of this shews the carinae and undulations very 
clearly, but is other ways smooth. The outer surface 
differs only in having numerous sharp fine decussating 
ridges upon it. The base is concentrically striated, and 
has a large umbilicus. 
Preserved in marl mixed with green sand, found in 
Marcham Field, near Oxford. 
