﻿Vol. 64.] m THE CARBONIFEKOUS ROCKS AT LOUGHSHINNT. 457 



The holotype ^ is preserved in the Geological Society's Collection 

 (E. 5460). 



In this specimen, a deep fossula extends to the centre, where it 

 forms a narrow chasm; near the wall it apparently expands 

 rapidly. Eight septa compose each lateral group ; the counter- 

 series consists of nineteen regularly-spaced septa, of which the 

 central one is more strongly pronounced. The lateral breaks are 

 conspicuous and de-pendent. 



Z. Ennishilleni, Thorns. & Nich. differs (1) in the closer approxi- 

 mation and more regular spacing of the septa ; (2) in the narrowness 

 of the fossula throughout its length. 



Enniskillenids from the Dublin sequence. — The 

 figured specimen from the lower part of P is the only example of 

 the typical species ; it is remarkable for the strong contraction 

 of the inner portion of the fossula. 



Zaphrentis aff. Ennishilleni from the CyatJiaxonia-Beds (' Eush 

 paper ' p. 315 & pi. xxix, fig. 2) differs in its smaller size, the 

 expanded inner portion of the fossula, and in the shortening of the 

 counter-septa (v. i). 



Enniskillenids from other areas. — The form figured by 

 Thomson & ISTieholson (v. s.) is common in the Lower Limestones 

 of Scotland. 



The Derbyhaven Limestone of the Isle of Man contains in 

 abundance a Zaphrentis^ which appears to agree in external charac- 

 ters with the type of Z. Enniskilleni. Horizontal sections exhibit 

 considerable looseness of septal grouping and a wideh'-gaping 

 fossula, constricted in its inner portion, but to a far less extent 

 than is the case in tlie specimen figured here." 



Z. aff. Enmslcilleni is common in Ds— 3 of Gower ^ ; it agrees 

 essentially with the species from D^ of Eush, but exhibits a 

 higher degree of specialization in the greater prominence of the 

 counter-septum, and in the deviation of the counter-septa from a 

 radial direction. 



Zaphrentis Omaliusi, var. ambigua, Carruthers. (PI. XLIX, 

 figs. 6 a & 6 h.). 



Z. cf. Phillipsi, vai\ (1), ' Rush paper ' p. 314. 



Z. Omalmsi, var. amhigua, Carruthers, Geol. Mag. dec. 5, vol. v (1908) 



p. 28, pi. iv, figs. 5 & 6. _ 

 (The figured specimens were identified by Mr. Carruthers.) 



Eig. 6 a exhibits well the bifossulate character of this variety, and 



1 The Council of the Geological Society very kindly granted permission for 

 the cutting of the specimen ; but, being doubtful of success, I shirked the 

 responsibility. 



^ The foregoing remarks are founded on the study of specimens collected 

 by Dr. Wheel ton Hind. 



^ This form will be fully described in a forthcoming paper on the Gower 

 sequence by IMr. E. E. L. Dixon and myself. 



