100 BRITISH AVONIAN CONODONT FAUNAS 
RANGE. North Crop 3D 8-3D 14/15. 
DescripTION. In broad morphology this subspecies resembles Gnathodus girtyi 
girtyi. The form of the anterior blade, and its general denticulation, the general 
outline and the size and depth of the posterior platform are generally similar. The 
number of denticles in the main blade (including the carina) ranges from 21 to 25. 
The distinctive feature of this subspecies is the denticulation of the posterior 
platform. The inner-lateral oral surface of the platform has a conspicuously 
developed, parapet-like series of denticles, those at the anterior end being higher than 
those at the posterior. These denticles are individually rather small and incon- 
spicuous, but the ridge which they form is itself made conspicuous by the general 
height and thickness of the base. They number about g, and are small rounded 
discrete node-like structures. Those at the anterior end of the series are separated 
from the carina by a shallow longitudinal groove. Towards the posterior end of the 
series the denticles converge with the main carina, which they meet near the anterior 
end of the fourth denticle from the posterior terminus of the unit. In lateral view 
these denticles form a conspicuous shoulder-like feature of the platform. The 
sloping anterior aboral margin terminates near the anterior end of the basal cavity. 
On the outer lateral platform, very indistinct node-like denticles may sometimes be 
developed but they are always a relatively inconspicuous feature, though in a very 
few specimens they are barely discernible in both lateral and oral view (e.g. Pl. 16, 
figs. 7a—-d). 
Gnathodus girtyi simplex Dunn 
Plate 16, figs. 1a—4d 
1957 Gnathodus girtyi Hass ; Bischoff : 24, 25, Pl. 4, fig. 21 (non Pl. 4, figs. 16, 17, 22, 23=G. 
girtyi givtyt Hass ; non Pl. 4, figs. 18-20=G. girtyi turritus Collinson & Druce. 
1957 Gnathodus girtyi Hass ; Ziegler in Fliigel & Ziegler: 40-41, Pl. 3, figs. 6, 9-13, 20., 
1957 Gnathodus bilineatus semiglabey Bischoff ; Ziegler 7m Fligel & Ziegler: Pl. 3, fig. 22 
(non Pl. 3, figs. 5, 8, 14, 23 =Gnathodus semiglaber). 
1959 Gnathodus texanus Roundy ; Voges: 284-285, Pl. 33, figs. 40-43. 
1960 Gnathodus clavatus Clarke (partim) : Pl. 4, figs. 7-9 (non pl. 4, figs. 4-6=Gnathodus 
givtyt givtyi Hass). 
1962 Gnathodus texanus Roundy ; Higgins : Pl. 3, fig. 28. 
1962 Gnathodus girtyi Form B Meischner : 31, text-fig. Io. 
1963 Gnathodus girtyi Form A Hass ; Bouckaert & Higgins : 17, text-fig. 3. 
1965 Gnathodus girtyi simplex Dunn: 1148, Pl. 140, figs. 2, 3, 12. 
Gnathodus girvtyi simplex Dunn ; Collinson & Druce in press. 
Di1aGnosis. Subspecies of G. givtyi in which lateral denticles on both inner and 
outer lateral margins of platform are more feebly developed than in G. girtyi girtyi 
and are also restricted to anterior and medial parts of platform. 
MATERIAL. 260 specimens : figured, X 107, X 108, IIO, III. 
Rance. North Crop CYD 7A-3D 23, Avon Gorge D 26. 
Description. In lateral and aboral views the main features of this subspecies are 
closely similar to those of G. girtyi girtyi especially in the form of the anterior blade 
