Vol. 68.] SUCCESSION IN THE NORTH-WEST OF ENGLAND. 557 



Transverse section. — If a set of serial sections be examined/ 

 it is found that in the earliest stages the central area is not com- 

 posed of vesicular tissue, but is occupied by a columella composed of 

 a number of thick, irregularly twisted, vertical lamellae, the majority 

 of which are continuous with the inner ends of the major septa. 

 The spaces between these are almost filled with secondary stereo- 

 plasm, which is also deposited thickly in the interseptal area. In 

 the later stages (fig. 3 c) the majority of the septa are discontinuous 

 with the lamellae: but the central columella remains attached, 

 even in the most mature stages, to one thickened major septum, 

 which appears in all cases to be the counter-septum. The medial 

 area is radiated by the major septa, which are rather thick and 

 blunt and few in number. In a transverse section having a 

 diameter of 17 mm. there are twenty-eight major septa ; these are 

 confluent at their bases to form a thick Zaphrentid type of wall. 

 The minor septa are inconspicuous in the earliest stages, and when 

 they first appear are entirely buried in the deposit of stereoplasm. 

 In adult forms they are never more than a quarter of the length of 

 the major septa. It is only in calicinal sections of big specimens 

 that dissepiments appear, when they form large loose vesicles of the 

 Carcinophyllum type. 



Longitudinal section. — The central area is composed of the 

 sections of the irregular twisted lamellae which form the columella ; 

 these are connected by loose vesicular tabulae, which pass outwards 

 to the epitheca in a highly irregular manner. 



This interesting species appears to be essentially a CarGinophylliim, 

 although it is not until the final growth-stages that the non-septate 

 dissepiments of that genus appear ; the curious contorted columella 

 is of a much simpler type than in any species hitherto described.^ 



Horizon and localities. — Seminula-gregaria Sub-zone, 

 Spirifer-furcatus Band and underlying bed, Meathop, Arnside 

 District ; and at the same horizon at Marten, Furness District. 



LOPHOPHYLLTJM MEATHOPENSE, Sp. nOV. (PI. XLYIII, figS. 2 a-2 6.) 



This species conforms exactly to the revised diagnosis of the 

 genus Lojphop)hyllum, as recently defined by Mr. Carruthers.^ 



Corallum. — Elongate -cylindrical, usually twisted, tapering 

 rather sharply at the curved proximal end. Epitheca thin ; 

 external surface covered with tine growth-lines and occasional 

 deeper constrictions. Specimens occur, measuring up to 25 cm. in 

 length and 3'25 cm. in diameter. Calyx deep : a specimen which 

 has the above-mentioned diameter at the base of the calyx has a 

 depth of calyx of 4*5 cm. 



Transverse section. — In the earlier stages (PI. XLVIII, 

 fig. 2 c) the major septa only are developed, and there is no peri- 



1 [When this paper was read, this form was described as a new genus — 

 Meathopia. Investigation of further material appears to render this separa- 

 tion unwarranted, as pointed out to me by Mr. E. Gr. Carruthers. — E. J. Gr., 

 i^ovemher 1912.'\ 



2 Trans. Eoy. Soc. Edin. vol. xlvii (1809) p. 152. 



