BRITISH AVONIAN CONODONT FAUNAS 173 
ularly so in outer view. There is a strong basal expansion below the posterior edge 
of the apical denticle, and in the anterior third of this, the basal cavity is deepest and 
widest, forming a biconvex pit. It is extended anteriorly and posteriorly as a shallow 
slit-like groove, but the posterior extension becomes indistinct near the posterior end 
of the margin of the expanded base. The anterior extension continues towards but 
does not quite reach the anterior end of the anterior blade. 
REMARKS. This species is close to O. compressa Rexroad, but differs from it in the 
shorter and deeper anterior and posterior bars and the short and relatively very 
broad apical denticle. 
Ozarkodina macer (Branson & Mehl) 
Plate 27, tigs. 7,8 
1934 Bryantodus macer Branson & Mehl: 283, Pl. 23, fig. 4. 
1934 Ozarkodina elongata E. R. Branson : 313, Pl. 28, fig. 25. 
? 1934 Bryantodus scitulus Branson & Mehl: 283, Pl. 23, fig. 5. 
1943 Bryantodus equalis Cooper in Cooper & Sloss : 170, Pl. 29, fig. 9. 
1943 Bryantodus cf. planus Branson & Mehl ; Cooper im Cooper & Sloss: 170, Pl. 29, 
fig. 3. 
1943 Ozarkodina regulavis Branson & Mehl ; Cooper im Cooper & Sloss : 170, Pl. 29, fig. 12. 
1943 Subbryantodus grandis Cooper in Cooper & Sloss : 175, Pl. 29, fig. 19. 
1949 Ozarkodina cf. elongata Branson & Mehl ; Thomas: 411, Pl. 4, fig. 28. 
1955 Ozarkodina vegularis Branson & Mehl ; Sannemann: 133, Pl. 6, fig. 5 only. 
1957 Ozarkodina willsi Rhodes & Dineley : 364, Pl. 38, figs. 1, 5. 
1957 Ozarkodina firma (Stauffer) Rhodes & Dineley : 364, Pl. 27, fig. 20. 
1957 Ozarkodina delicatula (Stauffer & Plummer) Bischoff : 39, Pl. 1, figs. 25-28. 
1957 Ozarkodina voundyi (Hass) Bischoff: 40, Pl. 2, fig. 2 only. 
1957 Ozarkodina congesta Stauffer, Bischoff & Ziegler : 75, 76, Pl. 12, figs. 18-20, Pl. 13, 
fig. 14. 
1958 Ozarkodina tortilis Tatge ; Huckriede: 154, Pl. 11, fig. 26 only. 
1959 Ozarkodina cf. delicatula (Stauffer & Plummer) Helms : 646, Pl. VI, figs. 14-16. 
1959 Ozarkodina cf. regularis Branson & Mehl; Helms: 647, Pl. IV, figs. 13, 14, (non Pl. 
IV, fig. 15=O. cf. congesta). 
1960 Ozarkodina vegularis Branson & Mehl ; Zimmermann : PI. IX, fig. 11 only. 
1960 Ozarkodina media Walliser ; Spasov : 68, Pl. 1, fig. 10 only. 
MATERIAL. 71 specimens : figured, X 304, X 305. 
Rance. Avon Gorge K 8-Z 38. 
Description. A gently arched blade with asymmetrical anterior and posterior 
blades, commonly bearing 5 to 7 straight, posteriorly inclined denticles on the 
anterior blade, and 8 to 12 straight posteriorly inclined denticles on the posterior 
blade. The denticles of the anterior and posterior blades may be of uniform eleva- 
tion, highest near the apical denticle and decreasing in elevation to the extremities of 
the blades, or they may be of variable elevation. The apical denticle is straight to 
slightly curved, posteriorly inclined and higher and wider than the blade denticles. 
The small circular basal cavity is situated beneath the apical denticle. The aboral 
edge is sharp. 
