114 BRITISH AVONIAN CONODONT FAUNAS 
Rexroad, but they agree in all the essential details with his description. Their most 
striking features are the deep and strongly antero-posteriorly compressed anterior 
bars, which diverge from each other at an angle of about 130°. They are relatively 
short, and bear on their oral surfaces up to 6 discrete and sharply pointed denticles. 
The two nearest the apical denticle and the distal denticle on each bar are small, but 
the three intervening denticles are larger and tend to increase in size distally. The 
ends of the anterior bar are bluntly spatulate, and the aboral margin is straight to 
feebly convex. The anterior face of the apical denticle is convex, the apical denticle 
itself being about twice the length of the largest denticle of the anterior bar, slender 
and pointed ; it tends to have rather feeble anterior lateral edges in its lower portion, 
but becomes sub-oval in cross-section towards its distal end. Both it and the 
denticles of the anterior bar tend to stand rather erect to the bar itself and are not 
obviously posteriorly recurved, although the denticles of the lateral bar tend to be 
inwardly curved towards the apical denticle. 
The posterior bar is long, slender, strongly laterally compressed and relatively deep. 
It has feebly convex lateral faces, and bears a series of up to 6 crowded, but apically 
discrete, laterally compressed, short denticles on its oral surface. A small pit below 
the apical denticle extends posteriorly as a faint groove along the posterior bar, and 
also along the proximal portions of the anterior bars. The posterior margin of the 
apical denticle is sharp-edged. Beneath the apical denticle the posterior-aboral 
margin of the anterior bar is excavated by an indented depression to join the basal 
margin of the posterior bar. 
Hibbardella (Hibbardella) parva sp. nov. 
Plate 25, figs. 21a, b 
Diacnosis. Hibbardellid with very small, delicate structure ; anterior bars 
flexed forwards diverging in vertical plane at a very obtuse angle. At their junction 
deeply indented aborally on anterior margin. Posterior bar strong ; apical denticle 
elongate, strongly laterally compressed. Basal cavity minute or non-existent. 
MATERIAL. 5 specimens : Holotype X 144 (figured). 
TYPE LOCALITY AND HORIZON. North Crop. Sample 3D 14/15. 
Rance. North Crop 3D 14/15. 
DESCRIPTION. The anterior bars are relatively deep, short and laterally com- 
pressed, and each bears about 5 oral denticles. They diverge anteriorly in a 
horizontal plane, so that the angle between them in a horizontal plane is about go°. 
They are little flexed in a vertical plane, and the angle between them is very obtuse. 
The aboral surface has a concave general appearance. This anterior curvature is 
most obvious in aboral view. It is relatively inconspicuous in oral view, where it is 
obscured by the development of the apical denticle, nor is it continued along the 
medial and distal parts of the bars which tend to straighten out and lie in a single 
plane relative to one another. 
Remarks. This species is closest to H. (H.) ortha Rexroad 1958, but it differs in 
