178 BRITISH AVONIAN CONODONT FAUNAS 
denticle of the anterior blade, and inclined to the posterior at an angle of 70°. Itis 
also three times the width of the blade denticles. The small circular basal cavity is 
situated beneath the apical denticle. The aboral edge is sharp. 
REMARKS. Ozarkodina cf. elegans, as interpreted in this study, is characterized by 
having longer denticles on the anterior blade than on the posterior blade. 
Ozarkodina sp. 
Plate 27, figs. 9-11 
MATERIAL. 93 specimens : figured, X 306, X 307, X 308. 
RANGE. Avon Gorge K 2-S 53. 
REMARKS. A number of broken specimens which contain part of the anterior, or 
posterior blades, have been found, but it is impossible to refer them to any species 
with certainty. 
Genus PATROGNATHUS gen. nov. 
DERIVATION OF NAME. From the Latin patey—father. 
DiaGnosis. Symmetrical platform conodonts, with lanceolate platform and 
short anterior median blade, generally of five denticles, the most posterior one of 
which is higher than the others. The platform bears a row of 6 to g nodes on either 
margin, separated by a central trough. The basal cavity is large, extending almost 
the complete length of the aboral surface of the platform, asymmetrical and laterally 
flared. A small posterior blade, composed of two denticles, is developed in a few 
specimens, but there is no carina extending along the platform. 
Type SPECIES. Patrognathus variabilis gen. et. sp. nov. 
DescriPTIOon. As for Patrognathus variabilis sp. nov. 
REMARKS. Patrognathus is similar to the previously described genera Taphro- 
gnathus Branson & Mehl, and Stveptognathodus Stauffer & Plummer, but has a wider 
and more flared basal cavity. Rexroad (1958A) considered Taphrognathus and 
Streptognathodus to be homoeomorphs, but Lindstrém (1964 : 173) considered Taphro- 
gnathus to be a synonym of Streptognathodus. The present authors believe Rexroad’s 
interpretation to be correct, and regard Patrognathus as another broad homoeomorph, 
which is present at the base of the Tournaisian and possibly in the uppermost Upper 
Devonian. 
Glenister & Crespin (1959) reported Taphrognathus from the Upper Devonian strata 
of the Fitzroy Basin in Australia. The specimens have an anterior blade which is 
lateral in position and, therefore, appear referable to our new genus Clydagnathus. 
Likewise Conil, Lys & Mauvier (1964) reported, but did not illustrate, Taphrognathus 
sp. from the Tny,-Tngp horizons of the Franco-Belgian Province. If the anterior 
blade is lateral in position, then their specimens should be referred to Clydagnathus 
gen. nov. Glenister & Klapper (1966, Pl. 94, fig. 3) have found specimens of 
“ Scaphignathus”’ in Australia identical to our Clydagnathus. In one sample it 
