134 THE AVONIAN OF THE AVON GORGE 
Figures (showing structure) : Nicholson, Manual of Palceon- 
tology. (1889), p. 310. 
Amflexus, 
Corallum simple, long and cylindrical, with a conical base ; 
thick- walled. 
Septa projecting from the wall, short and straight, of equal 
length and stopping abruptly ; attached to the upper surfaces 
of the tabulae. 
Tabulae very numerous ; extending completely across the 
tubes and horizontal throughout their extent, except in the 
immediate neighbourhood of the wall. 
Vesicles : none. 
Figures : Ed. and H. Plate 36 
This is one of the most remarkable coral genera and must, 
in my opinion, be restricted to the type species, Amflexus 
coTolloides, Sow. I cannot agree that there is any real affinity 
between Amflexus coralloides^ Sow. and the group typified by 
‘ Amflexus ’ nodulosus^ Phillips in which the septa are flexuous 
and unequal and the tabulae are sub-vesicular. The latter 
group appears to be an example of the reversion to simplicity 
which frequently precedes extinction. In a forthcoming 
paper, I am suggesting a new genus Pseudam'plexus, to include 
Amflexus nodulosus, Phillips and closely related species, all of 
which are mainly characteristic of D 3 . 
The ZAPHRENTIDS. 
(Including Zaphrentis and Ganinia). 
This group is distinguished among the Carboniferous Corals 
by the possession of a conspicuous radial depression (‘ Fossula ’) 
in each tabula ; the fossulse are so arranged as to always lie 
towards the same part of the corallum, and therefore to fit into 
one another from above downward. 
The septa are bilamellar and the two lamellis open out at 
