168 BRITISH AVONIAN CONODONT FAUNAS 
stand more or less erect to the basal surface of the bar, but those in the anterior three- 
quarters are inclined slightly anteriorly. The denticles are of variable height but 
there is no conspicuous increase or decrease in height in either direction. There isa 
slight tendency for the two denticles immediately posterior to the anterior denticle to 
be larger than the rest. The anterior denticle, which is not conspicuously large, is 
flexed sharply inwards, so that its inner lateral edge points inwardly and anteriorly, 
making an angle of about 140° with the posterior bar. When seen in inner lateral 
view, looking directly at the junction between the anterior denticle and the posterior 
bar, the angle between the posterior edge of the aboral process and the posterior bar 
is about 70°. The anterior denticle is more or less straight, with sharp and straight 
anterior and posterior edges and gently convex lateral faces. 
The aboral process is relatively short in comparison with the length of the denticles, 
with a rather sharp aboral point, and straight anterior and posterior edges. 
In outer lateral view the most conspicuous feature of the unit is the sharp lateral 
recurvature at a point about two or three denticles posterior to the anterior denticle. 
There is a faintly perceptible longitudinal bevelled edge developed, but the whole 
aboral surface of the unit is rather thin, although it is excavated by a longitudinal 
slit. There is a shallow, little-flared, posterior cavity below the posterior margin of 
the anterior denticle. 
Genus OZARKODINA Branson & Mehl 1933 
1933 Ozarkodina Branson & Mehl 51. 
TYPE SPECIES. Ozarkodina typica Branson & Mehl. 
Ozarkodina curvata Rexroad 
Plate 27, fig. 6 
1958 Ozarkodina curvata Rexroad : 24, Pl. 4, figs. 1-3. 
1961 Ozarkodina cuvvata Rexroad ; Rexroad & Burton: 1156, Pl. 141, figs. 13, 14. 
1964 Ozarkodina curvata Rexroad ; Rexroad & Furnish : 674, Pl. 111, figs. Io, 11. 
1965 Ozarkodina curvata Rexroad ; Rexroad & Nicoll: 25, Pl. 2, figs. I, 2. 
Ozarkodina curvata Rexroad ; Collinson & Druce (in press). 
MATERIAL. I specimen : figured, X 289. 
RANGE. North Crop CYD 7. 
DESCRIPTION. The most conspicuous feature of this species is the short, strongly 
depressed anterior bar, which bears a series of about 4 denticles on its oral edge. 
These are basally confluent, and only their apices are discrete, being sharply pointed, 
with gently convex lateral faces. They tend to be recurved parallel to the apical 
denticle, and show a more or less constant decrease in size anteriorly, those adjacent 
to the apical denticle being the largest. The anterior bar is relatively deep and 
relatively straight ; its anterior end is bluntly spatulate and its outer lateral face 
more or less flat. There is a rather flat bevel visible along the whole aboral edge of 
the unit, when seen in outer lateral view. The base of the apical denticle is about 
