Yol. 65.] CARBONIFEROUS LIMESTONE OF COUNTY CLARE. 581 



CLISIOPHYLLID LlTHOSTHOTION. (PI. XXVII, fig. 3.) 



This form, which is essentially similar to that figured by 

 Dr. Vaughan 1 from ~D 1 of the Bristol District, occurs in some 

 abundance near the base of D x in County Clare. 



Dibunophyllum. 



Dibtjnophylltjm aff. ip, Vaughan. (PI. XXVII, fig. 6.) 



In a horizontal section this form appears to be closely related to 

 Dibunophyllum \p. 2 It agrees with the Bristol form in the thick- 

 ening and extension of the mesial plate, and in the approximate 

 number of vertical lamella?. The central area is, however, less 

 strongly bounded, and its cuspidate nature is not well marked, 

 although the septal fossula is conspicuous. 



The minor septa are much more strongly developed in the Irish 

 form, even more so than in D. matlockense, Sibly, 3 and extend to 

 the inner wall. The latter feature is not so well defined as in the 

 typical Dibunophyllum \p. 



Carcinophyllum. 



Carcinophyllum sp. (PI. XXVII, fig. 5.) 



Porm conical, epitheca with faint longitudinal striations. 



Horizontal section. — The central area is nearly circular, 

 and has a sharply defined boundary. There is usually some indi- 

 cation of an irregular, thickened, mesial plate from which project 

 a number of vertical lamellae, which, as they approach the outer 

 margin of the area, assume a spiral arrangement and often produce 

 an open vesicular structure. 



The major septa are 35 to 37 in number, and the majority of 

 them reach the central area. The minor septa project inwards a 

 short distance from the inner wall. 



A septal break is marked by a considerable elongation of one of 

 the minor septa. The inner wall is very conspicuous, and forms a 

 dense ring due to the approximation and thickening of the outer 

 ends of the two series of septa. A narrow peripheral vesicular 

 ring is sometimes seen ; but, as rejuvenescence is common, it is 

 rarely developed to any great extent. 



Discussion. — This form, which is abundant at the top of S 2 in 

 County Clare, is closely related to Carcinophyllum mendipense from 

 Sj of the Mendip area, 4 agreeing with that species in the character 

 of the inner wall, the marked septal break, and the compressed peri- 

 pheral vesicular area, but differing in the nature of the central area 

 which, in the Irish form, is spiral in structure as opposed to radial. 

 It is distinguished from Carcinophyllum curheenense, Vaughan/ by 



1 Quart. Journ. Greol. Soc. vol. Ixi (1905) pi. xxiii, fig. 5. 



2 A. Vaughan. ibid. pi. xxiv, fig. 2a. 3 Ibid. vol. lxiv (1908) pi. i, fig. 2. 



4 See T. R Sibly, Quart. Journ. Geol. Soc. vol. lxii (1906) p. 369 & 

 pi. xxxi, fig. 4. 



5 Ibid. vol. lxiv (1908) p. 464 & pi. xlix, fig. 5. 



