﻿Vol. 66.] LIMESTONE SOUTH OF THE CRAVEN FAULT. 569 



Zaphrentis, Eafinesque & Clifford. 



Several species of this genus have been found in the area here 

 described, and in some cases individuals are exceedingly common. 

 The genus is quite rare in the white knoll limestones. 



Zaphrentis amplexoides, sp. nov. (PI. XXXVIII, figs. 1-9.) 



This is a remarkable coral which exhibits a number of features 

 associated with different genera. It is very common in Eylstone 

 Hail way Quarry, and there is thus plenty of material available for 

 study. I have, therefore, had quite a large number of specimens 

 cut and a considerable number of thin sections made. 



I was at first inclined to include it in Caninia, and Mr. Carruthers 

 suggested that it might be an Amplexus. I have, however, provi- 

 sionally assigned it to Zaphrentis, for reasons which will appear 

 later. It may, of course, be eventually transferred to one of the 

 other genera mentioned, or to Calophyllum, but meanwhile the 

 description of the coral as it occurs at Eylstone may be useful. 



In discussing its structure and possible relationships, I have 

 followed the diagnoses of the writers named below. Four closely 

 related genera are concerned, namely : — 



(a) Zaphrentis, Eafinesque & Clifford ; as re-defined by Mr. B. G. Carru- 



thers, in bis recent discussion of some species of this genus, Geol. 

 Mag. dec. 5, vol. v (1908) pp. 24 et seqq. 



(b) Caninia, Micbelin ; following the revised diagnosis, as given by 

 Mr. Carruthers in the Geological Magazine (torn. cit. pp. 158-59). 



(c) Amjplcxua, Sowerby ; as re-defined by Nicholson & Thomson, Ann. & 



Mag. Nat. Hist. ser. 4, vol. xvi (1875) p. 424. 



(d) Calophyllum, Dana; as re-defined by Thomson, Proc. Phil. Soc. 



Glasgow, vol. xiv (1882-83) pp. 358-59. 



It seems very doubtful whether the last genus will be retained, 

 as most or all of the forms assigned to it seem to fall within Am- 

 plexus or Zaphrentis as usually defined. 



Diagnosis. — Corallum simple, turbinate, conical and cylindro- 

 conical. Very variable in external outline, in this respect' being- 

 somewhat like Caninia cornucopias (see the diagram given by 

 Mr. Carruthers, op. supra cit. p. 160). When the growth is regular, 

 the coral is sharply and evenly curved until the cylindrical stage 

 begins. The latter is not very highly developed as a rule, fully- 

 grown specimens being the exception. The limits of variation in 

 form which I have seen are represented in fig. 5 (p. 570). 



The calyx is very different in different examples, owing to the 

 great changes in septal development as growth proceeds. Usually, 

 however, the septa are Amplexoid, and a large tabular area is seen. 

 In younger specimens a well-marked fossula is present. 



The development of the coral can, of course, only be satisfactorily 

 studied by means of serial sections, and I have had several series 

 made. In the very young stages, the septa are comparatively few 

 in number and very much thickened. They reach the centre in 

 the earlier stages. In these young specimens there is a cardinal 



