110 
THE AVONIAN OP THE AVON GORGE 
worth, while to hunt for specimens of fish teeth since they can 
always be obtained on the opposite side of the river.) 
(1) Below the ‘ Fish Beds.’ — 
Zaphrentis afi. Phillipsi is the only common species of Zaph- 
rentis. 
Athyris afi. glabristria and Orthothetes cf. crenistria are the 
most abundant fossils. 
Schizophoria afi. resupinata makes its first appearance, and 
is rather common, in the beds immediately above the slope. 
(2) Above the ‘ Fish Beds.’ — 
Zaphrentis afi. Phillipsi and Zaphrentis afi. cornucopiae are 
both very common and account for the greater number of coral 
sections which can be seen in the rock faces, but Amplexus, 
Michelinia and Syringopora can always be recognized if care- 
fully looked for. 
The large papilionaceous Chonetes is already firmly established 
as the dominant Chonetes and the genus of Syringothyris afi. 
euspidata is represented for the first time by the large form, 
Syringothyris euspidata, which is characteristic of the succeeding 
zone. 
Horizon 7. 
Diagnosis : — 
Caninia cylindrica is, for the first time, abundant and is 
associated with Zaphrentis afi. Phillipsi, which is still extremely 
common. 
N.B. — In the Avon section, Horizon 7 appears to be inseparably linked 
with the Z2 beds below and to be sharply marked off from the Syringo- 
thyris-Zone above, but this phenomenon is due to the incoming of peculiar 
physiographic conditions (the ‘ dolomite phase ’). Where the standard 
conditions persisted into the Syringothyris-Zone, as was the case in the 
Mendip Area, Horizon 7 presents its true character as a level of faunal overlap, 
although, here also, it is more closely linked with the Zaphrentis Zone below. ^ 
Fauna: — 
Syringothyris euspidata and papilionaceous Chonetes are the 
most striking of the Brachiopods, and there are few survivors 
of the Zj fauna. 
1 J. F. Sibly, Quart. Journ. Geol. Soc., vol. 62 (1906), pp. 330, 331. 
