BRITISH AVONIAN CONODONT FAUNAS 69 
Angulodus sp. nov. D 
Plate 29, figs. Ia—2c 
MATERIAL. 10 specimens : figured, X 40, X 41. 
LOCALITY AND HORIZON. North Crop, River Clydach, Nr. Gilwern, upper part of 
Lower Z Zone. Sample ZLA II. 
Rance. North Crop ZLA 8-ZLA 14, Avon Gorge Z 34-Z 38. 
DescripTIon. A simple bar unit similar to Angulodus sp. C but with a longer 
anterior portion of the posterior bar and a less marked and distinctly denticulated 
depression of the posterior termination. 
The apical denticle is fairly small, sub-circular in cross-section, inclined posteriorly 
and towards the inner side, so that it does not lie in the same plane as the other 
denticles or the rest of the unit. The anterior bar is short, massive, deflected 
through go° ; horizontal or feebly arched upward and then depressed through 90°. 
It commonly bears 4 to 5 stout, irregular, isolated, sub-circular denticles, which tend 
to be tallest in the anterior part. The anterior part of the posterior bar is one and a 
half to twice as long as the anterior bar. The oral surface bears 3 to 4 discrete 
pointed denticles, their diameter being about two thirds that of the apical denticle, 
and their cross-sections sub-circular to biconvex. They are inclined at about 45° to 
the posterior bar, and are separated by irregular smaller ‘‘ hindeodellid ”’ denticles. 
They tend to decrease in size posteriorly towards the point of depression. The 
posterior part of the posterior bar is depressed at an angle of 90°. It is very short, 
and its oral surface is limited to a single, large, fang-like denticle. This is strongly 
laterally compressed, with flat to gently convex lateral faces, and anterior and 
posterior edges. It lies almost parallel to the anterior part of the posterior bar. 
The posterior termination of the unit is pointed to sharply spatulate. A minute 
secondary denticle may be developed on the posterior edge of the most posterior 
denticle. The basal cavity is confined to the area below the apical denticle. The 
posterior bar commonly has a very fine aboral keel along its whole length. 
In aboral view the sub-apical pit is large and extremely shallow, approaching the 
form of an inverted basal cavity. 
Remarks. A form similar to this species is described by Bischoff & Ziegler 
(1957 : 43, Pl. 20, figs. 3, 6) as Angulodus gravis Huddle. The holotype of A. gravis 
differs greatly from the specimens figured by Bischoff & Ziegler, but there is a marked 
similarity between their forms and the present specimens. 
Genus APATOGNATHUS Branson & Mehl 1934 
1934 Apatognathus Branson & Mehl: 201. 
TYPE SPECIES. Apatognathus varians Branson & Mehl 1934 
Apatognathus bladus sp. nov. 
Plate 20, figs. 15a-16b 
DERIVATION OF NAME. From Latin blade. 
