26 E. G. Carrutheris — A Revision of some Carboniferous Corals. 



adult portions of a corallum ; they are never well developed, and are 

 often barely perceptible. 



The cardinal fossula is very generally a marked feature. Always 

 completely surrounded by the major septa, in the lower part of the 

 coral, it is broad and expanded at the inner end, but has a tendency to 

 narrow higher up in the corallum, and though in typical examples 

 a slight expansion of the central part is retained up to the floor of the 

 calyx (PI. IV, Figs. 1 and 4), continuous narrowing usually sets in 

 beyond that point. The cardinal septum completely divides this fossula 

 almost to the floor of the calyx, but latterly becomes much thinner 

 than its neighbours. In extent the cardinal fossula never seems to 

 reach beyond the centre of the coral, and usually falls short of it, 

 often to a considerable degree ; it would appear that sections cut 

 across the more strongly curved parts of the coral show a short, broad 

 fossula, and vice versa. 



A common and remarkable feature is the development of a counter 

 fossula through a slight enlargement of the two interseptal chambers 

 on each side of tlie counter septum. This character is almost always 

 present in some degree in the young stage of growth of a normal 

 example of the species (PI. IV, Figs. \a and 4a), and is often 

 persistent throughout. This counter fossula is proportionately longer 

 than the cardinal fossula, but, unlike the latter, of course never shows 

 any appearance of young septa at its base. The counter septum may 

 be either longer or shorter than its neighbours ; when longer it is 

 usually more markedly lobed at its inner end, thus approaching the 

 distinctive character of the genus Lophophyllum (PI. IV, Fig. \a). 



There is a tendency for the septa in each of the four quadrants to 

 fuse together at their inner ends, tlie fused ends meeting in the centre 

 of the coral. From this tendency arises the prominence of the fossulae. 



Dr. Vaughan's best figure is 2e (see Q.J.G.S., 1905, p. 269, pi. xxii). 



(b) Vertical Sections. — The arched tabulee, with their convex upper 

 surfaces, are of an essentially simple type. They lie from 1 to 2 mm. 

 apart, having depressions at each of the fossulse, the extent of these 

 depressions varying with the degree of development of the fossulae. 

 This being the case, the appearance of the tabulae varies according to 

 the direction of the section. Consequentlj', their nature is more 

 clearly shown, not by the usual vertical section, but by a contoured 

 figure of one of their number, as has been done by Dr. Vaughan, with 

 whose kind permission the accompanying text-figure is reproduced. 

 (See ante, p. 23, Fig. 2.) 



Localities. 



Millstone Grit : Greenfoot Quarry, near Glenboig, Lanarkshire (rare). 



Upper (?) Visean : Hollins Delf, and other quarries near Colne ; 

 Horrocksford Quarry, near Clitheroe (U '?). 



Tournaisian : Big Weston Wood Quarry, Portishead, near Bristol, 

 Clevedon, Failand, Woodspring ( Weston), and other localities in 

 the Zg subzone of the South- Western Province ; Burrington, 

 near Bristol (Zj subzone, rare) ; Rush Slates, co. Dublin 

 (especially K 4 a, the position of which is given in Q.J.G.S., 

 1906, p. 276, fig. 1). 



