BRITISH AVONIAN CONODONT FAUNAS 53 
gnathus gen. nov. and Spathognathodus plumulus plumulus sp. nov. Although these 
species are new, they show some resemblances to specimens described from other 
areas. 
Klapper & Glenister (1966) have described faunas from the Canning Basin of 
Western Australia. Their “‘ ? Scaphignathus velifera’’ is, according to Dr. Klapper 
(personal communication), probably congeneric with Clydagnathus, having a large 
basal cavity, which removes it from Scaphignathus. This species occurs in two 
samples. In one of these, it is not associated with other conodonts, and lies strati- 
graphically about 150 ft. below Spathognathodus aculeatus. In the other, it occurs 
with that species and with Palmatolepis glabra subsp. indet. It is clearly, therefore, 
of Upper Devonian age in this area. This does not necessarily imply an Upper 
Devonian age for the K Zone of the Avonian, however. The resemblance of the 
Australian specimens to those from the K Zone is not exact, and they may represent 
distinct species. The association of the Australian specimens with S. aculeatus 
implies an age within the costatus Zone and the Tn, of Belgium, but the absence of 
S. aculeatus in the Avonian K Zone conodont faunas suggests that they are of younger 
age. 
The presence of Spathognathodus costatus in the K Zone of the Avonian could imply 
an Upper Devonian age, but S. costatus, as we have now defined it, differs from S. 
costatus of German authors. The relative position of other Avonian genera makes a 
Carboniferous age even more probable. Our S. costatus is confined to beds in the 
Avonian lying above both Szphonodella and our single specimen of Elictognathus. 
Furthermore, the gnathodids, although they first occur 150 ft. above the position of 
S. costatus in the Avon Gorge, are advanced species which are of undoubted Carboni- 
ferous age in other areas. The earlier species of Gnathodus (G. kockeli etc.) are not 
represented in the Avonian faunas. 
Bouckaert & Ziegler (1965) have described a Fammenian conodont fauna from 
Belgium, in which are found five specimens of Scaphignathus veliferus (1965, Pl. 5, 
figs. 5-7) in a sample from the Montfort section at Esneux. These specimens 
probably represent the genus Clydagnathus, although they do not appear conspecific 
with forms from the K Zone. 
The genus Palmatolepis is characteristic of the Upper Devonian but Bischoff (1957) 
and Voges (1959) have reported Palmatolepis in the basal Cu I beds of West Germany. 
In North America, in the Mississippi Valley, Palmatolepis is abundant in the Saverton 
Shale, common to rare in the Louisiana Limestone and occurs rarely in the basal 
beds of the Hannibal. Collinson (1961) stated that ‘‘ the occurrence of Palmatolepis 
glabra and Palmatolepis gracilis in the European Lower Carboniferous, as well as in 
the Mississippi Valley Hannibal Formation, may represent stratigraphic admixture, 
but it seems more likely that they are indigenous ’’’. Specimens of the vast majority 
of Upper Devonian faunas yield abundant Palmatolepis, and the absence of palmato- 
lepids in the Avon Gorge provides some negative evidence in support of the assign- 
ment of the lowermost strata to the Carboniferous. 
Fewer than 2% (Klapper & Furnish, 1962 : Ziegler 1962, table 7 : Bouckaert & 
Ziegler 1965, Chart g) of the Upper Devonian faunas described lack Palmatolepis, and 
