﻿Vol. 66.~\ LIMESTONE SOUTH OF THE CRAVEN FAULT. 573 



The septa, as Dr. Vaughan points out, are straight and closely 

 approximated, and fuse together in a dense central mass. The 

 minor septa are well developed, especially those on each side of 

 the counter septum. The somewhat inconspicuous fossula is shown 

 by a shortened cardinal septum. The number of the septa is the 

 same in Dr. Vaughan's illustration as in my typical example, 

 namely, thirty. 



In the specimens that I have examined I do not find the alar 

 fossulae so well shown as in Dr. Vaughan's figured specimen. The 

 coral is very common in Hylstone Railway Quarry. 



Lophophyllum, Hichelin. 

 Lophophyllum costatum (M'Coy). (PL XL, figs. 1-4.) 



This is probably the same coral as that which was figured by 

 Dr. Vaughan as ' Cyailiaxonia ' aff. costata, M'Coy, 1 from Brad- 

 bourne (Derbyshire). It has been found abundantly by Dr. Sibly 

 in 'the shaly limestones overlying the Derbyshire massif.' Following 

 the revised diagnosis of the genus LojDliopliyllum recently given by 

 Mr. Carruthers, 2 the coral under consideration would fall within 

 that genus. It is exceedingly common in the Bylstone Railwa}^ 

 Quarry, where, in some shaly bands between beds of dark limestone, 

 it may be picked up by scores. 



The corallum is simple and often turbinate, sometimes having, 

 however, a cylindrical portion of some length. The maximum 

 length is about 2| inches, and the maximum diameter about 1 inch. 

 The columella stands up, in the weathered specimens more par- 

 ticularly, as a laterally compressed helmet-shaped boss, showing a 

 well-marked series of vertical striae. 



The external surface of the coral is marked with a series of fine 

 annular striations, through which, in specimens that show the 

 slightest sign of weathering, the traces of the septa may be seen. 

 ' Growth-constrictions ' are common, and thus the coral often 

 becomes somewhat irregular in shape. 



I have had a considerable number of these corals cut transversely 

 and some sections made. There is very great variation in the de- 

 velopment and mutual relationships of septa, dissepiments, tabulae, 

 and columella. It becomes increasingly obvious that serial sections 

 are necessary in the study of these variable corals, but such sections 

 seem to be more than usually necessary in this case. 



The septa reach the columella throughout the greater part of 

 the coral. In the latest growth-stages they begin to retreat in 

 groups, usually those nearest to the cardinal fossula earlier than 

 those nearer to the counter septum. The septa in the cardinal 

 quadrants are often very much thicker than the others, especially 

 in the earlier stages of growth. "When the septa have become 

 clearly detached from the columella, they often develop club-shaped 

 inner ends. At the same time the minor septa, which are but 



1 Quart. Journ. Geol. Soc. vol. lxii (1906) pi. xxix, fig. 5. 



2 Trans. Roy. Soc. Edin. vol. xlvii (,1909^) pp. 152-53. 



2 e2 



