86 BRITISH AVONIAN CONODONT FAUNAS 
MATERIAL. 20 specimens: Holotype X 75, Paratypes X 71, x 72, X 73, X 74 
(all figured). 
TYPE LOCALITY AND HORIZON. R. Clydach, Nr. Gilwern, K Zone. North Crop. 
Sample KL 5. 
RANGE. North Crop KL 1-KL 12, Avon Gorge K 12-K 17. 
DESCRIPTION. The blade is short, being only a quarter to a fifth the length of the 
platform. It is lateral in position, sub-triangular in profile and bears 4 to g fused, 
erect denticles with distinct apices. The largest denticle of the anterior blade is near 
the posterior end. The anterior aboral tip is bluntly spatulate. The platform is 
long and rather pointed, bearing lateral nodes separated by a medial trough, which 
usually deepens anteriorly (e.g. Pl. 1, fig. 11). In adult specimens the lateral ridges 
may coalesce medially, to form a sharply sinuous longitudinal ridge in the posterior 
portion, the medial trough then being confined to the anteriormost portion of the 
platform (e.g. X 72, Pl. 1, fig. 9). In other specimens the lateral ridges may be con- 
tinuous across the platform dividing it into a series of isolated laterally elongated 
troughs (e.g. X 73, Pl. 1, fig. 10), with a more or less prominent longitudinal marginal 
ridge on one side. The platform may be very slender, elongate and sinuous (e.g. 
X 74, X 75, Pl. i, figs. 13, 11). The posterior part may bear a short restricted carina 
of rounded, isolated nodes (e.g. X 75, Pl. 1, fig. 11) which can be produced as a short 
posterior blade. The inner oral rim of the platform is deflected through 80°, at the 
anterior end, so preventing the trough from opening anteriorly. 
The cavity is large, asymmetrical with thickened lips and is conspicuously laterally 
expanded. 
Remarks. This species is closely related to C. gilwernensis, from which it differs 
by having a lateral blade rather than a medial one. It can be distinguished from the 
genus Cavusgnathus by the closed medial trough and the ee gee gr type of 
asymmetrical sub-circular basal cavity. 
Clydagnathus darensis sp. nov. 
Plate 2, fig. 6a—7d 
DERIVATION OF NAME. From the type locality at Daren Ddu. 
DiaGnosis. Clydagnathid with relatively low, short anterior blade, consisting of 
4 or 5 more or less erect denticles, those at the anterior end being only slightly 
smaller than those at the posterior. 
MATERIAL. 23 specimens : Holotype X 77, Paratype X 76 (both figured). 
TYPE LOCALITY AND HORIZON. R. Clydach, Nr. Gilwern, Lower Z Zone. Sample 
ZLA. 27. 
RANGE. North Crop ZL 3-ZLA 27, Avon Gorge K 17. 
DESCRIPTION. The unit is asymmetrical, the blade always being on the right 
when viewed from the posterior. The blade is low, consisting of 4 or 5 denticles all 
of approximately equal height, the tallest denticle being either the posterior or the 
