﻿Vol. 64.] IN THE CAEBONIFEKOUS ROCKS AT LOUGHSHINNr. 



465 



ClisiojjJiyllum' on account of itsseptation) ; and the third from the 



Holmpatrick Limestone. 



The central cylinder is entirely built up of a great number 



of strongly and uniformly- arched tabulae, fitting one over the other, 



and bound together by thin radiating lamellae. (This cylinder is 



easily separable from the septal tube which surrounds it.) 



The central area 



Fig. 16. — A new genus of CUsiophyllid : of a horizontal sec- 

 diagram constructed from a specimen tion consequently 



. found in Dg-s at Wkton (Derbyshire). exhibits a series of 

 (Magnified 2% diameters,) very close conceutric 



intersections radiated 



by thin flexuous 

 lamellae. A small 

 area at the very 

 centre is usually 

 entirely free from 

 structures of either 

 kind (except when 

 the section is tan- 

 gential to one of the 

 tabulae). 



The major septa 

 are thick, equal aud 

 close - set, and the 

 septal ring is practi- 

 cally unbroken at 

 any point. Tnter- 

 septal vesicles are 

 very scarce, and con- 

 sequently the septa 

 have nearly smooth 

 sides. There is no ex- 

 ternal vesicular ring, 

 but the septa are 

 firmly attached to 

 the wall. Minor 

 septa are conspi- 

 cuously developed, 

 but project a very 

 short distance in- 

 wards from the wall. 

 The earliest Clisio- 

 phyllids are simple 

 examples of this 

 type, agreeing in the 

 regular ring of septa 

 firmly attached to the wall, in the absence of a differentiated 

 external area, and in the structure of the central cylinder. The 



later forms are, however, more highly developed. 



A = Horizontal section. 

 B = Solid specimen dissected and restored, 

 showing tlie central cylinder. 



