136 
THE AVONIAN OP THE AVON OORGE 
The fossula is a conspicuous radial gap which separates the 
two lateral sepfcal groups. 
The lateral breaks are usually less conspicuous and separate 
the antifossular group from the two lateral groups. (These 
breaks are usually represented by the shortening of a pri- 
mary septum on either side of the corallum.) 
In each lateral group, the septa are confluent at their inner 
ends and form a wedge-shaped mass. 
In the antifossular group, the two bounding septa usually 
meet and form a single plane which bisects the corallum. The 
rest of the septa of the group converge towards this plane 
without, as a rule, meeting one another. 
Tabulae arched in the centre (‘ cystoid ’) and deeply de- 
pressed in the region of the fossula. 
Vesicles : In the neighbourhood of the wall, the tabulae 
split up into broad shallow vesicles which are directed upward 
and outward. 
A calyx view exposes the deep fossula and the three 
septal groups ; the secondary septa are more conspicuous in 
this view than in a horizontal section. 
Figures: Ed. and H. Plate 34 
Caninia, 
Corallum simple, elongate, cylindro- conical and usually 
large. 
