CARBONIFEROUS CORALS AND BRACHIOPODS 97 
wedge -arrangement due to intermural gemmation. Exter- 
nally, the weathered corallites are seen to be arranged in 
successive storeys of basaltiform prisms. 
Tabulae cannot be made out with certainty in all vertical 
sections, but occasionally very thin, regular tabulae can be 
seen, and it seems probable that they are absent from 
most of the tubes, simply because their extreme thinness 
has rendered them easy of destruction. 
The walls of the tubes are very thick and, in a horizontal 
section, numbers of small corallites can be seen starting 
in the thickness of the walls, especially in the corners. 
Projections from the walls can apparently be occasionally 
made out, but are not by any means usual. 
The figure represents a vertical section, natural size. 
• There are two fine specimens in the collection, obtained 
from behind the Colonnade (i.e. from almost the highest 
beds in the Carboniferous Limestone). 
I have included this species under Chmtetes, rather than 
under Alveolites, on account of the gemmation being 
normally intermural and not fissiparous, but the occasional 
presence of projections inwards from the walls indicates 
a close relationship to Alveolites septosa. 
Syringopora. 
The specimens in the collection are not numerous and are 
poor in quality ; they give a very imperfect idea of the 
great abundance of this genus almost throughout the 
series. Again, horizontal sections are very unsatisfactory, 
since they only register the diameter and infilling of the 
corallites and their average separation, v/ithout affording 
any accurate estimate of the flexion of the tubes or of the 
vertical spacing of their connectors, except in so far 
as it is possible to roughly deduce these characters from the 
obliquity of the sections and the number of cross sections 
which are in connexion. 
