Vol. 62/J LIMESTONE OF THE MEXDIP AREA. 367 



by Dr. A. Vaughan, in the following characters : — (1) Larger, more 

 widely-conical form ; (2) more numerous septa (there are forty to 

 forty-five primary septa) ; and (3) longer secondary septa, which 

 project inwards well beyond the thickened wall. 



Caninoid Cyathophylla. (PI. XXXI, fig. 1.) 



Compare: — Caninia cylinclrica (Seouler), mut. y, Vaughan, Quart. Journ. Geo!. 

 Soc. vol. fad (1905) p. 273 & pi. xxiii, fig. 1. 

 Cyatkophyllwm <p, Vaughan, ibid. p. 274 & pi. xxiii, figs. 3-3 b. 



In the Syringothyris-Zone of the Mendip area l occur some very 

 interesting corals, the characters of which are intermediate between 

 those of Caninia cylinclrica and Cyathophyllum (f>. Individual speci- 

 mens exhibit considerable variation, and the following descriptive 

 notes deal with the general characters. PI. XXXI, fig. 1 illus- 

 trates a specimen in which the Caninoid characters are somewhat 

 accentuated. 



Form : large, cylindrical to cylindro-conical. 



The tabulae form broad, flat plates, a majority of which extend 

 completely across within the inner wall; they bend downward 

 outside the inner wall. The fossula forms a well-marked, parallel- 

 sided, shallow groove. The primary septa run in along the face of 

 a tabula, extending almost to the centre. 



Horizontal section. — Primary septa, 65 to 80 in number. 

 A minority only of the primary septa extend actually to the outer 

 wall ; but the peripheral, purely-vesicular area is narrow and 

 inconstant, while both the outer wall and the vesicles show numerous 

 septal projections. 



The external area, radiated by both series of septa, is narrow. 



The secondary septa project inwards for a short distance from the 

 inner wall. 



The septa are never strongly thickened, except in the immediate 

 neighbourhood of the inner wall, nor do they show any special 

 thickening near the fossula. 



The fossula, occupied by a shortened primary septum, is indicated 

 by an inward shift of the tabular intersections. The two primary 

 septa bounding the fossula are practically parallel one to the other. 



Interseptal vesicles, representing tabular intersections, are very 

 few in the medial area, radiated by the primary septa. 



Resemblances and differences. — The corals of this type 

 resemble Caninia cylinclrica, mut. y in the nature of the tabulae, 

 and in the possession of a purely-vesicular peripheral area ; but differ 

 from the typical form of that coral in the thinness of the peripheral 

 vesicular area, in the more numerous, slightly-thickened septa, and 

 in the weaker development of the fossula. 



Cyathophyllum closely resembles the forms under description 

 in the character and the large number of the primary septa, 

 and in the nature of the septal break. It differs, however, in the 



1 Nearly identical forms occur in the Syrivyothyris-Zoue of the Weston- 

 super-Mare district. 



2c2 



