﻿582 MR. A. WILMORE ON THE CARBONIFEROUS [Nov. I9IO,. 



From Troller's Gill and Apple tree wick I have collected specimens 

 which, have very closely packed corallites, but the verticillate cha- 

 racter is not sufficiently developed to adopt the name S. geniculates, 

 Phillips. Still, there is a definite tendency towards geniculate? 

 (PI. XL, figs. 7 & 8, and PI. XLI, figs. 1-4). 



In the other direction geographically, there is a marked tendency 

 towards variation in another definite direction. In the district of' 

 Rain Hall, Thornton, and Broughton, the ramulose character becomes- 

 predominant. The number of transverse tubuli decreases, and the 

 amount of dichotomous branching increases to such an extent that 

 the latter is almost the only method of increase seen. 



Thus S. aff. reticulata seems to vary in a well-defined mauner 

 both laterally and vertically. It is obvious, however, that much 

 more work will be necessary before these tentative conclusions can- 

 be considered as finally settled. The expense and time involved 

 in the preparation of the necessary sections — both transverse and 

 longitudinal — are considerable, and the writer hopes to continue to> 

 devote himself to this and to the other problems mentioned. 



In the Swinden Moor district — that is, west of the district dealt 

 with in this paper — a coral which I regard as S. elistans (Fischer) is 

 plentiful. It has corallites measuring approximately 2 millimetres 

 in width, and 3 to 4 mm. apart as a rule. There are pronounced 

 geniculations at the origin of the transverse tubuli, and these are a 

 considerable distance apart. There is very little dichotomous 

 branching. The funnel-shaped tabulae are beautifully seen in some 

 weathered specimens ; they are somewhat irregularly developed, and 

 the medial tube is not of so pronounced a character as it is in 

 the strongly reticulate forms found at Swinden, Elbolton, and 

 Appletreewick. 



There is also the somewhat rare form which I have classed as; 

 8, gigantea, Thorns. This occurs chiefly at the lower horizon, that 

 is, below the Caninia-gigeintea beds. Its coralla measure 2| mm., 

 in width, and are sometimes as much as 6 mm. apart. Connecting- 

 tubes are few, and dichotomous branching is not common. The- 

 walls are thick, and there is a deposit of peripheral tissue in most 

 of the specimens that I have seen. I hope to collect more material,, 

 and to obtain more particulars of this interesting ' species.' 



Finally, as to some points of internal structure. There is seldom 

 a well-developed axial tube, except in the forms with large corallites, 

 and then not always. The strongly reticulate coralla from Elbolton 

 and the knoll region generally show a medial tube fairly well 

 (PI. XLI) ; the coralla which I have included in S. distans show it 

 less perfectly, but still it may usually be seen. The small reticulate 

 forms from Hetton and Bell Busk rarely show a medial tube ; their 

 tabulae are much fewer in number, and are often approximately 

 horizontal, hence no medial tube can be developed by their 



