72 BRITISH AVONIAN CONODONT FAUNAS 
away from the apical junction. The anterior bar is relatively short and straight with 
a flat outer lateral face. It bears up to 7 denticles, not including the apical denticle, 
and these are basally confluent but apically discrete. Their outer lateral faces are 
strongly convex and they have sharp anterior and posterior edges and they decrease 
in size towards the anterior tip. The apical denticle is about twice as long as the 
largest of the denticles of the anterior bar. It is inclined posteriorly and is paralleled 
by the denticles of the anterior bar ; it is straight with a very strongly convex outer 
lateral face and sharp anterior and posterior edges ; it is not expanded on the outer 
aboral margin. The posterior bar is very slightly shorter than the anterior, and its 
denticles are conspicuously smaller ; they are of more or less subequal height and 
they are about 7 in number. They are basally confluent but apically discrete with 
sharp anterior and posterior edges and feebly to gently convex outer lateral faces ; 
these are less conspicuously convex than the faces of the anterior denticles ; on 
the outer lateral aboral margin of the posterior bar there is a more or less con- 
spicuous longitudinal ridge developed parallel to the base. We take this to be the 
“laterally tumid ”’ character referred to by Clarke (1960). The angle of divergence 
of the two bars when viewed from the outer lateral side is about 30°-40° ; they 
are also strongly flexed inwardly and join each other at an angle of about 40° in the 
inner lateral view, in such a way that the denticles of the posterior bar are erect and 
those of the anterior bar point outwards towards the observer. The bars are strongly 
flexed inward and the denticles curve inward, as well as posteriorly ; the denticles 
of the posterior bar are inclined anteriorly and tend to parallel the main denticle. 
The inner lateral faces of both the anterior and posterior bars are flat and a rather 
bevelled aboral edge is developed from them, excavated throughout its length by a 
narrow, slit-like cavity, which does not increase markedly in size below the apical 
denticle. 
Remarks. Clarke’s illustration of Hinde’s specimens makes it clear that the 
characteristics of the species are the relatively larger size of the denticles adjacent to 
the apical denticle, and the almost platform-like lateral edges developed on the 
posterior bar. 
Apatognathus petilus Varker 
Plate 20, figs. 12a-14b; 17a, b 
1967 Apatognathus petila Varker : 135, 136, Pl. 17, fig. 11, Pl. 18, figs. 7, Io, If. 
MATERIAL. 23 specimens : figured, X 50, X 51, X 52, X 53. 
Rance. North Crop CYD 7-3D 14/15, Avon Gorge C 7-C 16, D 7. 
DEscRIPTION. The orientation of these units is arbitrarily defined by regarding 
the longer bar as posterior, although the inclination of the apical denticles does not 
always justify this. Apatognathus with slender elongated lateral bars continuously 
and strongly recurved and flexed ; apex of arch formed by them marked by develop- 
ment of 5 large denticles, of which three medial are largest but no single apical 
denticle is conspicuously larger than rest. 
