﻿Yol. 64.] m THE CAEBONIFEEOTJS EOCKS AT LOTJGHSHINNY. 459 



X new species of Densiphylloid Zapheentis. (PI. XLIX, 

 fig-. 2.) 



Compare Zcqyhrentis sp. (?), Thorns, oj). cit. pi. vi, fig. 19, and Bensiphylkim 

 chariest onense, Thorns, o^p. cit. pi. vi, fig. 21. 



The adult species is characterized by its straight, closely- 

 approximate septa, the thickened ends of which are fused together 

 into a dense central mass. The intermediates are short, but con- 

 spicuous. The cardinal septum is shorter than the rest. 



The fossula is inconspicuous, and, being bounded by two straight 

 septa, is constricted as in the D mutation of Z. Delanouei, referred 

 to by Mr. R. G. Carruthers.^ Alar breaks can be made out without 

 difficulty. 



The tabular intersections are almost completely circular. 



At an earlier stage the section appears to agree with Zcijjilirentis 

 sp., Thoms. The young stage shows a parallel-sided fossula and 

 de-pendent alars as in Z. Delanouei. Hence this species is probably 

 a Densiphylloid derivative from the Z.-Delanouei gens. 



Differences from similar forms. — (1) Densij^Tiyllum rusJi- 

 ianum. Our species has straighter and more numerous septa, 

 distinct lateral breaks and intermediates, and a wall of normal 

 thickness. 



(2) Zajphrentis Delanouei, constricted mutation, Carruthers (loc. 

 cit.), has the same type of fossula, but differs in the smaller number 

 of septa, the suppression of intermediates, and in the much closer 

 approach to Z. iJelanouei observable in young sections. 



(3) DensipJiyllum charlestonense, Thoms. Oar species appears 

 to differ in its prominent intermediates and in the central massing 

 of the septal ends. [Mr. Carruthers (op. cit. pp. 27 & 30) considers 

 D. charlestonense to be closely comparable with Z. Omaliusi var. 

 densa.] 



The typical form occurs only in the BibunopJiylhim-Ijimestone. 

 A similar (probably identical ^) form is found commonly in the 

 Lower Limestones of Scotland and in D2_3 of Gower. 



Densiphyllum eushiantjm, sp. nov. 



Bensiphyllum, Vaughan, ' Rush paper ' p. 318 & pi. yxix, fig. 6. 



Sufficient material being now to hand, this species can be 

 definitely named. 



Form elongate, cylindro-conical, laterally compressed, usually 

 but slightly cornute. Wall very thick ; epitheca smooth, uncon- 

 stricted. 



Horizontal section. — The most striking characters are (1) the 

 very thick wall ; (2) the regularity of the septa and the absence 

 of alar breaks ; and (3) the constriction of the inner end of the 

 fossula. 



The septa are well spaced, and thickened at their attachment to 



1 Geol. Mag. dec. 5, vol. v (1908) pp. G5-66. 

 '^ Fide E. G. Carruthers. 



