BRITISH AVONIAN CONODONT FAUNAS 169 
two to three times as wide as the largest denticles adjacent to it, and is confluent with 
them. It is recurved posteriorly but has a more or less straight posterior edge and is 
bluntly pointed. It has sharp anterior and posterior edges. Its outer lateral face is 
feebly convex, and the basal margin is sharply, but not greatly, outflexed below it to 
give a rather inconspicuous navel. The posterior bar is about twice the length of the 
anterior, but is less deep. It is straight along its aboral margin and the distal end 
makes an angle of about 90° with the distal end of the anterior bar. The posterior 
bar decreases in depth posteriorly and bears a series of crowded confluent denticles, 
more or less of similar size. These number up to about I1 or 12, and have rather 
sharply pointed free tips. They show no overall trend in size, but the posterior ones 
tend to be slightly smaller than the rest. Germ denticles are visible between some of 
them. Those near the anterior end of the posterior bar tend to be inclined posteri- 
orly, but those towards the distal end of the bar stand more or less erect to the base 
of the bar itself. The whole posterior bar is sharply inflexed at about its mid-length, 
so that its inner lateral face is longitudinally concave. The posterior aboral corner 
of the unit is sharply rounded. In inner lateral view, the inward curvature of the 
unit is a very conspicuous feature. 
There is a small basal cavity below the posterior edge of the denticle, around which 
the basal margins flare slightly. This is continued as a conspicuous but narrow slit 
along the anterior and posterior bars. 
Ozarkodina compressa Rexroad 
Plate 27; fig: 23 
1957 Ozarkodina compressa Rexroad : 36, Pl. 2, figs. f, 2. 
1958 Ozarkodina compressa Rexroad ; Rexroad: 24, Pl. 6, figs. 1, 2. 
1961 Ozarkodina compressa Rexroad ; Rexroad & Burton: 1156, Pl. 141, figs. 16, 17. 
1964 Ozarkodina compressa Rexroad ; Rexroad & Furnish : 674, Pl. 111, fig. 9. 
1965 Ozarkodina compressa Rexroad ; Rexroad & Nicoll: 24, 25, Pl. 2, figs. 3, 4. 
MATERIAL. 12 specimens : figured, X 420. 
Rance. Avon Gorge C 3-S 49, North Crop 3D 14/15-3D 22. 
DESCRIPTION. The present specimens are broadly similar to those described by 
Rexroad and other authors, although they differ slightly in that the posterior bar 
Denticles _- Apical denticle 
Posterior Anterior 
Posterior bar Anterior bar 
Lip of basal cavity 
Fic. 33. Ozarkodina sp. showing morphological terms used in the text. 
