166 BRITISH AVONIAN CONODONT FAUNAS 
1957. Neoprioniodus varians (Branson & Mehl) Rexroad : 35, Pl. 2, fig. ro. 
1958 Neoprioniodus varians (Branson & Mehl) Rexroad : 24, Pl. 5, figs. 3, 4 
1961 Neoprioniodus varians (Branson & Mehl) Rexroad & Burton: 1155, Pl. 140, figs. 9, 
10. 
1965 Neoprioniodus vavians (Branson & Mehl) Rexroad & Nicoll: 24, Pl. 2, fig. 18. 
MATERIAL. 7 specimens : figured, X 281. 
RANGE. North Crop CYD 7-3D 17. 
DESCRIPTION. The present specimens have a conspicuous and relatively short 
anterior denticle, which is very wide at its base in comparison with its length. It is 
regularly tapered, its anterior and posterior edges being straight, and its distal tip 
pointed. Its inner lateral face is strongly convex in the proximal portion and less 
strongly convex in the distal portion. It is extended aborally as a very short aboral 
process, with a straight anterior edge and a continuously concave posterior edge, 
which is continuous with the concave margin of the posterior bar when viewed in 
lateral view. Its inner lateral face is only feebly convex, and there is no sharp inner 
basal flexure. 
The posterior bar, when seen in inner lateral view, is continuously and relatively 
strongly curved downward. It decreases in depth posteriorly and its posterior 
aboral corner is bluntly rounded. Its lateral face is strongly convex in the anterior 
half, but flat to feebly convex in the posterior part, its basal margin being slightly 
bevelled. Its oral surface bears about 16 large denticles, between which there are 
some smaller “‘ germ’ denticles developed, especially in the anterior third. The 
denticles as a whole are closely crowded, but the major denticles are generally not 
confluent with one another. The denticles in the median half of the bar tend to be 
rather larger in size than the rest. The denticles on the posterior quarter of the bar 
are the smallest. All the denticles stand more or less erect to the basal surface 
below them, and have sharp anterior and posterior edges and convex lateral faces. 
They are short and bluntly pointed. 
The anterior denticle stands erect to the oral surface of the eee Se bar in contact 
with it. It is also gently curved inward along its length. 
In outer lateral view, there is a very conspicuous bevelled edge along the whole of 
the aboral margin. The outer lateral face of the anterior denticle and the aboral 
process is more or less flat in the lower proximal portion, but becomes gently convex 
in the distal two-thirds. The curvature of the posterior bar is very conspicuous, and 
the bar decreases in depth posteriorly. In lateral view the anterior end of the aboral 
process is slightly flexed outward in a horizontal plane, and the main part of the 
posterior bar is gently flexed inward, so that its inner lateral face is concave. There 
is a deep and obvious basal cavity below the posterior part of the anterior denticle, 
which decreases in width but is continued as a rather wide extension along both the 
aboral process and the posterior bar. 
Neoprioniodus sp. nov. A 
Plate 22, fig. 14 
MATERIAL. I specimen : figured, X 282. 
