Vol. 62.] IN THE CARBONIFEROUS ROCKS AT RUSH. 321 



(1) This early form has a small central area, distinguished in a 

 horizontal section by the strength and close approximation of the 

 concentric intersections. The external area is very narrow, and 

 for the most part merely radiated by septal teeth, which project 

 into it from the thick outer wall. 



(2) The central type occurs somewhat commonly in the Curkeen 

 Limestone. In this form the external area is finely vesicular, and 

 the septal prolongations which radiate the area are thin and in- 

 conspicuous. (Hence the differentiation of the external area is a 

 conspicuous feature.) The central area is broader, and its structure 

 looser, than in the earlier form. 



Examples from the South-Western Province. — The 

 earlier form occurs in the upper part of the Syringothyris-Zone ; 

 and I have a specimen from the Upper Dibunophyllum-Zoiie of 

 Pendine that is almost identical with the Curkeen type. 



EXPLANATION OF PLATES XXIX & XXX. 



Plate XXIX. 



Avonian Corals from Rush. 



K Fig. 1. Syrinyopora cf. reticulata, Goldf. (p. 313). Horizontal section and 

 calices ; natural size. R 10 k. Megastoma-Beds ; coast-section, Rush. 

 2. Zaphrentis aff. Enniskitteni, Edwards & Haime (p. 315). Horizontal 

 section; X 1*2. R21g. Cyathaxonia-Beds ; coast-section, Rush. 

 Figs. 3, 3 a, & 3 b. Cyathaxonia rushiana, sp. nov. (p. 316). 



Fig. 3. View of calyx and exterior (taken at 45° to the plane of symmetry) ; 

 natural size. Cyathaxonia-Beds ; Bradbourne (Derbyshire). 1 

 3a. Horizontal section of the same specimen ; X If. 

 3 b. Weathered fragment (showing the axial tube and enclosed 

 columella); natural size. R21d. Cyathaxonia-Beds ; coast- 

 section, Rush. 

 < Figs. 4 & 4 a. Cyathaxonia contorta, sp. nov. (p. 317). 



Fig. 4. View of exterior (the calyx-wall is removed to show the columella); 

 natural size. R 18 c. Cyathaxonia-Beds ; coast-section, Rush. 

 4a. Horizontal section of a larger specimen; X 1*2. R21d. 

 Cyathaxonia-Beds ; coast-section, Rush. 

 Fig. 5. ' Cyathaxonia ' aff. costata, M'Coy (p. 318). Horizontal section ; X 1*5. 

 Cyathaxonia-Beds ; Bradbourne (Derbyshire). 



6. Densiphyttum (Zaphrentoid subdivision) (p. 318). Horizontal section ;. 



X If. R21d. Cyathaxonia-Beds ; coast-section, Rush. 



7. Amplexi-Zaphrentis, subgen. nov., variant convergent on Zaphrentis aff. 



Enniskitteni ($. 315). Horizontal section ; X 1*2. R21 d. Cyathaxonia- 

 Beds ; coast-section, Rush. 



1 I had intended to illustrate this species solely from the Irish material ; 

 but, although specimens are abundant in the Rush section, the matrix does not 

 lend itself readily to the cutting of good slices. The photograph of one such 

 slice was quite unsatisfactory ; and, though five more slices were cut, none of 

 them was sufficiently good to serve as a representation of this ver} r important 

 zonal form. I consequently had to fall back upon the more tractable material 

 from Bradbourne (Derbyshire). I can see no essential differences between the 

 Bradbourne and the Rush forms. 



