BRITISH AVONIAN CONODONT FAUNAS 109 
Gnathodus ? sp. nov. 
Plate 18, figs. 7a—c 
MATERIAL. I specimen : figured, X 92. 
LocaLiTy AND HORIZON. North Crop. Sample ZL 8. 
Rance. North Crop ZL 8. 
Description. A gnathodid ? with transversely ridged posterior half of platform ; 
anterior part of platform unornamented except for marginal nodes. Base deeply 
excavated. Anterior bar unknown. 
The anterior blade is broken but the platform is preserved. The carina consists 
of a row of low nodes ; in the posterior half of the platform, a row of smaller nodes 
runs either side of the carina, with which they fuse to give a series of trinodate 
transverse ridges. The inner platform is expanded slightly more than the outer, and 
both are unornamented, except for a short marginal row of fused nodes occurring in 
the anterior half and diverging posteriorly. 
In aboral view the cavity occupies the whole area of the platform and is grooved 
along its mid-length. 
REMARKS. This species is unlike any described gnathodid and does not bear any 
obvious phylogenetic relationship to other species. 
Gnathodus sp. 
Plate 17, figs. 4a—d 
MATERIAL. I specimen : figured, X 138. 
RanGe. Scotland HOSIE 2A. 
DeEscripTIon. A single specimen of Guathodus appears to be close to G. girtyi, but 
differs from it in the character of the lateral denticles of the posterior platform. In 
the present specimen the development on the two lateral areas of the platform is 
highly asymmetrical, and the platform of the inner-lateral margin, which begins 
anterior to the point of origin of that on the outer-lateral margin, is short, and 
consists of only three or four fused blunted denticles. Just anterior to its fusion 
with the carina, a less conspicuous fused, inner series of lateral denticles is developed 
on the outer-lateral platform. These become confluent with the carina just in front 
of its posterior termination, but do not reach the posterior end of the carina. The 
apron is wide and flaring, and is asymmetrical in both oral and aboral views. In 
lateral view the denticles of the anterior blade are sharp and erect, and those of the 
carina are also sharply tipped and distinct, standing higher than the lateral denticles 
on either side of the platform. The denticles of the inner lateral process form 
blunted parapet-like nodes in lateral view. The denticles of the carina decrease 
rapidly in size towards the posterior in the posterior half of the platform. 
