164 BRITISH AVONIAN CONODONT FAUNAS 
recurved in its upper portion. In inner lateral view, it is concave in its anterior 
proximal portion and feebly convex in its posterior proximal portion. It is elongated 
and more or less sharply pointed, the anterior and posterior edges being straight. 
The aboral process is strongly developed, with a concave to straight anterior margin, 
and a continuously convex posterior margin. Its lateral faces are flat in the anterior 
portion, but the base of the inner lateral side is strongly flared to give a conspicuously 
spatulate appearance. Its anterior edge has 2 or 3 minute denticles developed on it 
which are of smaller size than any on the posterior bar. 
The posterior bar is short and relatively deep. It bears more than 6 denticles, 
which are more or less erect or only slightly posteriorly inclined to the bar, and which 
are discrete for at least half their length. They are regularly pointed and have feebly 
convex lateral faces and sharp anterior and posterior edges. In outer lateral view 
the whole unit is conspicuously bowed inwards. In aboral view the most conspicuous 
feature is a continuous slit-like groove, which runs to the anterior aboral point of the 
anterior aboral process and along its mid-line, being continued as a narrowing slit 
along the posterior bar. 
The posterior bar is much thinner than the aboral process but the basal groove is 
not conspicuously expanded below the process. It is, however, slightly wider behind 
the posterior part than it is below the anterior. The lateral aboral faces of the aboral 
process are more or less straight in aboral view, the basal margin being widest below 
the posterior end of the process and then curving inward sharply towards the 
posterior bar. The aboral faces are more or less flat. 
REMARKS. Collinson & Druce (in press) include this species as a junior synonym 
of N. singularis (Hass). We have only a single specimen in our collections and 
we are not in a position to determine the range of morphological variation. 
Neoprioniodus tulensis (Pander) 
Plate 21, figs. Iga, b 
1856 Prioniodus tulensis Pander (partim) : 30, Pl. 2a, fig. 1 only. 
1928 Prioniodus tulensis Pander ; Holmes (partim) : 22, Pl. 3, fig. 18 only. 
1940 Prioniodus cassilavis Branson & Mehl : 186, Pl. 6, figs. 11, 12, 15, 17. 
1950 Prioniodus cassilavris Branson & Mehl ; Youngquist, Miller & Downs: 528, Pl. 67, 
figs. 23, 24. 
non 1957 Prioniodina cassilaris (Branson & Mehl) Bischoff: 47, Pl. 5, figs. 38, 39 (=N. 
pevacutus). 
1963 Neoprioniodus tulensis (Pander) Rexroad & Collinson : 18, Pl. 2, fig. 17, 22, 23. 
MATERIAL. 5 Specimens : figured, X 280. 
Rance. North Crop CYD 6-CYD 7. 
Description. The distinctive feature of the present specimens is the long, 
recurved, bluntly pointed anterior denticle, the broad spatulate form of the aboral 
process, and the elongated posterior bar, which bears a series of about 15 denticles 
onits oral surface. These denticles are discrete for most of their length, and decrease 
in size posteriorly. 
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