102 
THE AVONIAN OP THE AVON GORGE 
Km = Phase of Modiola lata. 
From the base of the Carboniferous series up to the ‘ Palate 
Bed,’ the majority of the fossils are forms characteristic of 
shallow water, and very incomplete information can be obtained 
concerning the fauna which was then living in water of the 
depth which we have selected as our standard. This portion of 
the sequence, therefore, presents us with a special phase, and 
the change of fauna which takes place at its termination does not 
indicate the extinction of an earlier fauna and its replacement 
by a new, but merely introduces us to the life of a lower bathy- 
metric-zone. 
Diagnosis : 
The abundance ,pf shallow- water fossils (Modioliform lamelli- 
branchs, Ostracods, Spirorhis, etc.), associated with Brachio- 
pods which are characteristic of the Lower Cleistofora-Zone 
(Athyris Royssii, Eumetria, etc.). 
Flora: • > , . 
Plant fragments (common). • 
Fauna: ' \ 
Sfirorhis {?), Ostracods and Crinoid fragments. 
Lamellibranchs of the geneta Modiola^ Sanguinolites, etc. 
Gasteropods, especially small forms belonging to the genera 
Murchisonia and Bdlerophon. 
Bryozoa belonging to the genera Rhabdomeson, Rhombopora 
and Fenestella. 
Fish scales (somewhat rare). 
The Brachiopods include shallow water forms such as Lingula, 
‘ Discina,^ together with a limited number of species which also 
belong to the fauna of standard depth : — 
Athyris Royssii (abundant). 
Eumetria sp. 
Eumetroid Ehynchonellid. 
Spiriferids (fragments, probably of both Spirifer and Syringo- 
thyris). 
Chonetes cf. hardrensis. 
