122 BRITISH AVONIAN CONODONT FAUNAS 
Hindeodella hibbardi Collinson & Druce 
Plate 28, figs. 18-20 
1957 Angulodus walvathi (Hibbard) Bischoff : 17, Pl. 5, figs. 44, 45. 
1961 Angulodus walrathi (Hibbard) Higgins Pl. ro, fig. 16. 
Hindeodella hibbardi Collinson & Druce in press. 
MATERIAL. 22 specimens : figured, X 167, X 168, X 169. 
RANGE. North Crop 3D 11-3D 14/15. 
DESCRIPTION. This species of Hindeodella is characterized by a relatively long 
anterior lateral process, which is one third to one quarter the length of the posterior 
bar, and which is depressed and deflected at the bottom. Immediately anterior to 
the main denticle the anterior lateral process is depressed at an angle of about 110° 
to the posterior bar. Then, at a distance of about one quarter of its total length from 
the main denticle, it is inflexed by lateral twisting, so that the denticles anterior to 
this point of inflection point both inwards and also are curved upwards. Ata further 
point about two-thirds of its length from the main denticle, it is again depressed in a 
vertical plane, and the remaining 3 distal denticles of the anterior lateral process are 
larger and more strongly recurved than those behind them. The oral surface of the 
anterior lateral process bears up to Io stout denticles, more or less sub-circular in 
cross-section, discrete, tending to increase in size distally from the main denticle, 
although the most anterior is smaller than those immediately behind it. The 
process becomes thinner towards the anterior end, the antero-aboral extremity being 
bluntly rounded or plough-like in general form. The proximal end of the anterior 
lateral process and virtually the whole length of the posterior bar have conspicuously 
and strongly convex lateral faces. The denticles of the posterior bar are strongly 
developed, and curve inward, being inclined posteriorly at an angle of about 45°. 
The denticles of the main series are each separated by up to 4 smaller, fused, crowded 
denticles, which are less than half the length and diameter of those of the larger 
series. The posterior third of the unit is slightly depressed vertically and is deflected 
laterally. 
A very conspicuous aboral groove runs the whole length of the unit, being wide but 
rather shallow, and having conspicuous lateral lips. It is reduced in width towards 
the anterior and posterior end, and is widest below the main denticle where it is 
marked by a more or less conspicuous biconvex pit, both ends of which are relatively 
pinched in relation to the rest of the cavity. The outer lateral face is rather less 
convex than the inner. 
The main denticle is relatively small and inconspicuous in comparison with other 
denticles of the series. The whole unit is elongate, but in some specimens the lateral 
faces tend to be less convex than others, giving the whole unit a more slender 
appearance. In complete specimens the aboral cavity is seen to extend only for 
about half the length of the posterior bar. 
