﻿Yol. 64.] CAEBONIFEROUS LIMESTONE OF THE MIDLAND AREA. 71 



thinner and slightly flexiious in the external area. Their inner 

 ends fall short of the columella by a considerable distance. The 

 broad external area, which is rather closely vesicular, is radiated 

 both by the primary septa, which extend to the outer wall, and by 

 a secondary series of septa. The latter extend from the outer wall 

 inwards almost, or quite, to the inner wall, which is defined by the 

 closer approximation of the innermost rows of dissepiments. The 

 septal fossula is generally inconspicuous. 



In a median vertical section, the columella forms a strong, 

 continuous median line. The broad central area is occupied by sub- 

 vesicular tabulge which are distinctly elevated centrally. The tabulae 

 bend downwards at their outer ends, and merge into large vesicles 

 which constitute a narrow medial area. The external area is broad, 

 and formed by very small vesicles, arranged in outwardly ascending 

 rows. 



Dimensions. — The type-specimen is about 2*5 centimetres in 

 diameter at the calyx, and about 5'd cm. in length. 



Horizon. — Koninckopliyllum i)roprium occurs in D^ in the 

 Midland area. 



Discussion. — Typical representatives of the genus Konincko- 

 phylltim^ bear considerable resemblance to Litliostrotion. In 

 addition to their usually simple habit of growth, they are dis- 

 tinguished from the latter genus by (1) the more rudimentary 

 development of the primary septa, which are only very slightly 

 produced over the broad tabulae ; and (2) the greater development 

 of the external, vesicular zone. 



Koninckophyllum propriwn exhibits all the essential characters 

 of a typical Koniyichophyllum. It differs from Koninckophyllum 

 magnificum, Thoms. & Mch.,- the genotype, in the following 

 respects : — (1) Its smaller size. (2) The nature of the external 

 area, as seen in horizontal section : in Koninckopliyllum proprium 

 the external area is filled with more or less rectangular dissepiments ; 

 in X. magnificum the vesicular structure of the external area is 

 much closer, and to a large extent highly irregular, so that the 

 septa can only be traced with difficulty. (3) The wider spacing of 

 the tabulae, which are less markedly subvesicular. (4) The stouter 

 nature of the columella. 



Koninckophyllum sp. 



A Koninckophyllum, occurring in D.^ in the Midland area, exhibits, 

 in horizontal section, thin spidery septa, an external area not very 

 closely vesicular and not strongly demarcated, and a very small 

 columella. This is, apparently, a distinctive form ; but the imperfect 



'^ Foi" an accurate description of the germs Koninekophi/llu77i, see J. Thomson 

 & H. A. Nicholson (the authors of the genus) in Ann. & Mag. Nat. Hist. ser. 4, 

 vol. xvii (1876) pp. 297-300. 



2 Figured in Ann. & Mag. Nat. Hist. ser. 4. vol. xvii (1876) pi. xii, figs. 2 

 & 2a ; and in Proc. Phil. Soc. Glasgow, vol. xiv (1882-83) pi. xi, figs. 1 & 1 a. 



