160 BRITISH AVONIAN CONODONT FAUNAS 
posterior bar is strongly laterally compressed and is relatively thin, being more or less 
triangular in section, with the aboral edge being the widest. The lateral faces are 
flat to feebly concave. The denticles of the posterior bar are strongly laterally com- 
pressed and are confluent for most of their length. They are bluntly pointed and 
have more or less sharp anterior and posterior edges, their lateral faces being feebly 
biconvex. The denticles proper are about twice the length of the posterior bar. 
The anterior denticle is very strongly developed; it is massive in general form, being 
about five times the length and two or three times the width of the largest denticles 
of the posterior bar. It is slightly recurved posteriorly, but its distal portion is more 
or less straight. It has very sharp anterior and posterior edges and is so strongly 
compressed in lateral view that it has a sword-like appearance. It is bluntly 
pointed. Its inner aboral lateral face is very strongly extended inwards, and this is 
a most conspicuous feature of the unit in lateral view. Its outer lateral face is feebly 
convex to flat in the lower part and is gently convex in the upper portion. The 
whole unit is very slightly curved in a horizontal plane, the inner side being feebly 
concave. In aboral view the most striking feature is the wide flaring of the inner 
lateral aboral edge around the junction of the anterior denticle and the posterior bar. 
The outer lateral face is less conspicuously flared. The whole aboral surface below 
this lateral flexure is excavated, culminating in a deep median pit which is restricted 
in its area, but extends anteriorly and posteriorly as rather conspicuous longitudinal 
grooves along the anterior portion of the anterior denticle and along the posterior 
bar. The posterior aboral edge of the anterior denticle makes an angle of about 120° 
with the straight edge of the posterior bar. The antero-aboral corner is very slightly 
convex and the junction with the edge is more or less pointed. 
Neoprioniodus montanaensis (Scott) 
Plate 22, figs. 5a—8b 
1942 Lochreia montanaensis Scott (partim) : 289, Pl. 29, fig. 9 only, Pl. 40, fig. 12. 
1941 Prioniodus barbatus Branson & Mehl; Ellison & Graves (partim) : 3-4, Pl. 1, fig. 25 
only. 
1953 Prioniodus singulavis Hass : 88, Pl. 16, fig. 4. 
1956 Prioniodus cf. singularis Hass ; Elias : 112, Pl. 2, fig. 45. 
1956 Prioniodus voundyi var. dividen Elias : 110, Pl. 2, figs. 39-41. 
1957 Prioniodina alatoidea (Cooper) Bischoff: 45, Pl. 5, figs. 33, 34, 36. 
1957 Prioniodus sp. A Ziegler in Fliigel & Ziegler : 50, Pl. 4, fig. 3. 
1958 Neoprioniodus singularis (Hass) Stanley : 471, Pl. 66, figs. 2, 3. 
1958 Neoprioniodus sp. A Stanley : 472, Pl. 66, figs. 4, 5. 
1961 Neoprioniodus singularis (Hass) Higgins : Pl. 11, fig. 5. 
1962 Neoprioniodus singularis (Hass) Higgins: Pl. 1, fig. 8. 
1963 Neoprioniodus singularis (Hass) Bouckaert & Higgins : 17, fig. 3. 
Neoprioniodus singularis (Hass) Collinson & Druce (in press). 
MATERIAL. 232 specimens : figured, X 268, X 270, X 269, X 271. 
RANGE. North Crop CYD 6-3D 1g. 
DESCRIPTION. The most distinctive feature of this species is the long, slender, 
