132 
THE AVONIAN OF THE AVON GORGE 
Chcetetes is a Monticuliporoid genus distinguished by im- 
perforate walls and by a fissiparous manner of growth. 
If ‘ Alveolites ’ alf. septosa be referred to Chcetetes, the septal 
projections must be regarded as infolds of the walls, brought 
about by incomplete fission of the corallites.] 
Figures: Ed. and H. Plate 45 
Michelinia. 
Corallum massive ; the base usually covered with a thick 
wrinkled epitheca. 
Corallites : large contiguous prismatic tubes connected by 
numerous conspicuous mural pores. 
Septa numerous, but projecting a very short distance into 
the tube so that the inner surface of the calyx appears to be 
longitudinally ribbed. 
Tabulse vesicular, convex upward and very rarely stretching 
completely across a tube. 
The calyx-view of a well-weathered corallum presents 
a remarkable resemblance to a honeycomb ; the floors of the 
calices are strongly convex, as if the tubes were filled with 
large bubbles ; the walls of the calices are closely ribbed by 
the septal ridges. 
Ahorizonta] section exhibits the vesicular infilling 
of the tubes and, in many places, the walls are interrupted 
where the plane of section has cut along a mural pore. 
A vertical section shows the characteristic wedge- 
like manner of growth, and the interior of the tubes is seen to 
be filled with a mass of large bubbles, all convex upward and 
in very few instances stretching completely across a tube. 
Figures: Ed. and H. Plate 44 
‘ Beaumontia ’ includes species of Michelinia in which the 
tubes are narrower and more elongate than is the case in 
Michelinia proper, and in which the tabulae are only slightly 
convex and usually stretch completely across the tubes. 
