176 WELLBURN : FISH REMAINS IN THE LIMESTONE SHALES. 
base is semicircular, thick, strong, and extends horizontally more 
or less at right angles to the cones of the crown, and its under- 
side is concave at the centre. The root is not well shown. Of 
the crown of the teeth, only the central cusp is shown in one 
tooth, the other showing (in impression) the central and one 
lateral cone. The characters of the cones are well shown in the 
former tooth, which is very well preserved ; it is thick, circular, 
and very strongly attached to the base, abruptly tapering, slightly 
inclined backwards, and from each side of the cone — slightly 
below its apex — a sharp cutting edge runs laterally on to the base. 
The lateral cone is not well shown, but it appears to lean slightly 
outwards, and it — as well as the central cone — shows well-marked 
longitudinal striae running from the base upwards. 
Form, and Loc. : Limestone Shales (Yoredales) Crimsworth 
Dean. 
Order : Selachii. 
Sub-order : Asterospondyli. 
Family : Cestraciontidse. 
Genus : Orodus Agassiz, 1838. 
0. elongatus Davis, 1883 (ex Agassiz M.S.). 
x\nother specimen in the collection of Dr. Hind shows 
several more or less imperfect teeth of the above species. 
The teeth are very long in proportion to their width, one 
— although the whole length is not shown — being extremely so, 
the length of the part shown being 22 mm, whereas the greatest 
width is only 3 mm. In this specimen the central prominence 
is imperfect, but the lateral ridges extending from it towards 
the extremities of the tooth are well shown, especially on the 
longer lateral prolongation, and from this lateral carina secondary 
ridges branch out irregularly on either side, the longer ones 
reaching the basal margin, the shorter ones soon disappearing, or 
in some instances two converge and unite to form a V-shaped 
fold, which also soon disappears. The basal margin is smooth 
and slightly sulcated, and the base in this tooth appears to have 
a porous structure and to be slightly wider than the crown. 
