BRITISH AVONIAN CONODONT FAUNAS 71 
lateral view the lateral walls of the bar and the denticle faces are flat, and the whole 
unit is continuously recurved so that all denticles point inward. The slight lateral 
flange on the outer aboral lateral face of the anterior bar and the wide posterior 
aboral surface are conspicuous features. 
Remarks. Although our specimens are fragmentary the distinctive size and 
character of the denticles, as well as the form of the base, appear to set this species 
apart from all those previously described. 
Apatognathus chauliodus Varker 
Plate 20, figs. 1a, b, ; 2a, b 
1967 Apatognathus ? chaulioda Varker : 129, 131, Pl. 17, figs. 1-3, 5. 
MATERIAL. 2 Specimens: figured, X 44, X 550. 
RANGE. Avon Gorge D 7. 
DescrirTion. The bars diverge at an angle of 25°-35° and in inner lateral view 
are inclined inwards to slightly face one another. The apical denticle is as wide as 
the prominent bar cusps, widest at its base and sharply pointed. It is slightly 
curved and inclined to the posterior. A prominent denticle is present on each of the 
lateral bars. These bar cusps are equal in size to the apical denticle, but are 
separated from it by up to 5, but commonly 2 or 3, small compressed denticles, 
which are shorter in length than the depth of the bar and are fused with one another. 
The denticles of the bar adapical to the bar cusp may be longer than the height of the 
bar, and are discrete. The aboral edge of the bar is straight, but the bar itself 
increases in depth towards the apex from its shortest depth at the adapical extremity. 
The bar denticles are slightly inclined inwards. The aboral edge of the bars is sharp, 
an aboral groove is present and the basal cavity beneath the apical denticle is 
circular. 
Apatognathus geminus (Hinde) 
Plate 20, figs. 3a—4b, 6a—7b 
1900 Prioniodus geminus Hinde: 344, Pl. 10, fig. 25. 
1928 Prioniodina ? gemina (Hinde) Holmes: 1g, Pl. 5, fig. ro. 
1960 Apatognathus geminus (Hinde) Clarke : 4, Pl. 1, figs. 1, 2. 
1963 non Apatognathus ? gemina (Hinde) Rexroad & Collinson: 7, Pl. 1, figs. 12-17. 
(=A patognathus scalena Varker). 
MATERIAL. 4 specimens : figured, X 54, X 55, X 56, X 57. 
Rance. North Crop CYD 6-3D 14/15, Avon Gorge C 16. 
DEscRIPTION. The most distinctive features of this species are the prominent 
apical denticle and the large size of two denticles on the anterior bar adjacent to that 
denticle. The whole unit is strongly recurved and strongly laterally flexed, so that 
in outer lateral view the aboral surface is visible along almost the whole length of the 
unit. Both bars are strongly flexed inwards so that the denticles appear to radiate 
