BRITISH AVONIAN CONODONT FAUNAS 43 
A gap is present in the conodont record of the lower part of the Caninia Dolomites 
(Samples C 26-C 28). Dr. S. C. Matthews (personal communication) has a small 
fauna of anchoralis—bilineatus interval aspect from an oolitic facies in the Mendips, 
which represents the lateral equivalent of the Caninmia Dolomite. This fauna 
correlates with part of the Cu II 6 of Western Europe and with the Keokuk Formation 
of North America. 
Cavusgnathus unicornis—Apatognathus libratus Assemblage Zone 
CHARACTERISTIC SPECIES : Apatognathus libratus Varker, Cavusgnathus unicornis 
Youngquist & Miller, S. cristulus Youngquist & Miller, M. beckmanni Bischoff, 
Gnathodus cuneiformis Mehl & Thomas, Cavusgnathus charactus Rexroad, and 
Cavusgnathus cristatus Branson & Mehl. 
Limits: The lowest occurrence of the zone in the Avon Gorge coincides with the 
oldest stratigraphic occurrence of Cavusgnathus unicornis Youngquist & Miller, 
although the true base of the assemblage zone cannot be accurately defined because 
of the absence of conodont faunas in the Caninia Dolomite. One sample (C 39) of 
the Canina Dolomite has yielded a fauna containing C. umicornis Youngquist & 
Miller and M. beckmanmi Bischoff. This indicates that at least the upper part of the 
Canima Dolomite is within this assemblage zone. The upper limit of the assemblage 
zone coincides with the oldest stratigraphic occurrence of Taphrognathus varians 
Branson & Mehl, which is found in the Upper Sz Subzone. 
REMARKS: This assemblage zone occupies the CzS; Zone and the lower and 
middle of the Sg Subzone (Samples C 39-S 44). Together with the overlying 
Taphrognathus varians—Cavusgnathus—A patognathus Assemblage Zone, it is equiva- 
lent to the middle and upper part of Cu II 8 in Europe and to the Warsaw, Salem, 
and lower part of the St. Louis Formation of North America. 
The very small number of conodonts present in this stratigraphic interval precludes 
a more detailed division, although the presence of G. cuneiformis Branson & Mehl at 
the base of the assemblage zone may provide the basis for future correlation. The 
overall aspect of the conodont faunas from this and the overlying conodont assembl- 
age zone of the Avonian are similar to those described by Rexroad & Collinson (1963 
and 1965) (see p. 61 for detailed discussion). 
Taphrognathus varians—Cavusgnathus—Apatognathus Assemblage Zone 
CHARACTERISTIC SPECIES: TJ. varians Branson & Mehl, C. unicornis Youngquist 
& Miller, and S. cristulus Youngquist & Miller. 
Limits : The limits of this assemblage zone coincide with the stratigraphic range 
of T. varians Branson & Mehl as at present known in the Avonian. 
REMARKS : This assemblage zone is present in the upper part of the Sz Subzone 
of the Avonian (Samples S 45-S 58). It is tentatively correlated with the lower part 
of the St. Louis Formation of North America. It is equivalent to the uppermost 
Cu II § in Germany. 
Specimens transitional between Cavusgnathus and Taphrognathus, which are 
