578 MR. J. A. DOUGLAS ON THE [Nov. I909, 



Densiphyllum. 



Densiphyllum sp. (PI. XXVII, fig. 7.) 



This form, which occurs in the topmost beds of the limestone in 

 County Clare, seems in its type of septation to bear some relation 

 to Cyathaxonia costata, M'Coy, but lacks the central axis of that 

 genus. 



Campophyllum. 



This genus was revised in detail by Thomson in 1893, 1 who 

 includes in it those corals which are intermediate in structure 

 between Calophyllum on the one hand and Cyatliophyllmn on the 

 other. 



Mr. R. G. Carruthers has recently shown 2 that the genotype of 

 Michelin's genus Caninia is Caninia cornucopia?, and the results 

 of his investigations seem to indicate that the reasons given 

 by Thomson for the inclusion of the forms commonly known as 

 Caninia cylindrica and C. gigantea, which are regarded by that 

 author as distinct species, in the genus CampopJiyllum, at least 

 merit further consideration. Horizontal sections, however, cut near 

 the base of Campophyllum cylindricum, show a striking resemblance 

 to certain stages of growth in Caninia comucopice, and it thus appears 

 doubtful whether the two species should be assigned to different 

 genera. (In County Clare, the first maximum of C. cylindricum 

 occurs at the same level, Horizon y, as that of C. cornucopia?.) 



CAMPOrHTLLTJM CYLINDRICUM (Scouler). (PI. XXVII, fig. 8.) 



The mutation of this species which is common at Horizon y is 

 characterized by a broad vesicular outer zone, completely radiated 

 by the two series of septa ; in this respect it resembles the 

 form characteristic of S, in the South-Western Province of Great 

 Britain. It possesses, however, more numerous and thinner septa, 

 its structure being somewhat Cyathophylloid in appearance, though 

 the septal fossula and associated thickened septa are strongly 

 marked. 



A characteristic mutation, distinguished by the abnormal de- 

 velopment of the minor septa, is also abundant at the base of S x . 

 These septa project some distance from the strong inner wall into 

 the median area, where, together with the major septa, they become 

 greatly thickened. Their inner ends have a rounded or blunt ap- 

 pearance, totally distinct from the tapering points of the major septa. 

 The vesicular outer zone is similar to that of the form mentioned 

 above, being radiated by the two series of thin septa, with several 

 rows of interseptal vesicles. 



1 Proc. Roy. Irish Acad. ser. 3, vol. ii, pp. 667-758 & pis. xv-xxi. 



2 Geol. Mag. dec. 5, vol. v (1908) p. 158. 



