42 ME. J. A. DOUGLAS ON GEOLOGICAL SECTIONS [vol. lxxvi, 



Visean of Europe (as, for example, Litliostrofion and the Clisio- 

 phyllids). are entirely unrepresented. Its most remarkable feature 

 is the abundance of small Zaphrentid corals showing a certain 

 degree of resemblance to Lophophyllam and Oyaihaxonia. 



Since some confusion still appears to exist as to the exact 

 limitations of these genera, I have added a short discussion on 

 their relationship with the forms here described. 



Palseontological Notes. 



Of the specimens which I have termed Lophophylloid Zaphrentids 

 many appear to be closely related to the corals figured and described 

 as Lophophyllum by Thomson & Nicholson in 1876, 1 agreeing with 

 them in general size and form, in the absence of any external zone 

 of vesicular tissue, and in the possession of a longitudinally-ribbed 

 epitheca and a clavate columella joined at one extremity with a 

 single septum. The latter, however, was described as hying within 

 the septal fossula. whereas in the present case it is invariably the 

 counter-septum that is elongated. 



Although classed as Lophophylla, their relationship with Za- 

 phrentis is admitted : the onty essential point of difference being 

 the presence of a ' central columellar eminence.' 



Of late years, Mr. K. G. Carruthers has shown, from an 

 examination of Belgian topotypes, that the genotype of Loplio- 

 phyUum (L. JconincJci Edwards & Haime) had a smooth epitheca, 

 and is synonymous with Cyathaxonia tortuosa of Michelin. In 

 the absence of the original holotypes, LopJiophyllwm tortuosum, 

 as redefined by Mr. Carruthers, must, therefore, be taken as the 

 type, and the forms described hj Thomson & Nicholson can no 

 longer be referred to this genus, which, differs from them in 

 possessing a smooth epitheca. well-developed minor septa, and a 

 zone of dissepiments. 



If Vaughan was correct in assigning the fauna here described 

 to the extreme summit of the Avonian sequence, these corals cannot 

 be considered as phylogenetically intermediate between Zuplirentis 

 and LopliopliyUum : for, according to Mr. Carruthers, the latter 

 genus is already typically developed in the Tournaisian, whereas 

 Zaplire ntis does not approach extinction until the close of Avonian 

 time. It is equally impossible to regard these Zaphrentid corals 

 as derived from a Lophophylloid ancestor. Any tendency in one 

 or other of the two forms towards the development of a similarity 

 of structure must, therefore, be ascribed to convergence or coeval 

 assimilation. 



Mr. Carruthers has recently given an instructive description 

 of the evolution of Zaplvrentis delanonei : and some of the later 

 members of that gens, predominant in the Upper Limestone Croup 

 and Millstone Grit of Scotland, show in their ephebic stages a 

 marked resemblance to the forms described here. A comparison, 



1 Ann. & Mag. Nat. Hist. ser. 4, vol. xvii (1876) pp. 126-28 & p]. viii, figs. 3-7. 



