﻿Yol. 66, ,] LIMESTONE SOUTH OF THE CRAVEN FAULT. 567 



I recognize four species from the area under discussion, namely : — 

 Caninia gigantea, Mich., 0. hettonensis, sp. nov., G. subibicina, 

 M'Coy, and C. cornucopia?, Mich. 



Caninia gigantea, Mich. (PI. XXXIX, figs. 4, 5 & 7.) 

 [For synonymy, see papers quoted above, p. 566.] 



The general characters of this species, as I know it from this 

 area, are as follows : — The maximum diameter is a little over 

 3 inches. I have not obtained a complete specimen, but many 

 individuals more than a foot in length may be seen. 



Characters seen in transverse sections. — There is a 

 peripheral area of rather large vesicles, then an area of smaller 

 dissepiments, reaching to a fairly well-defined inner wall. The 

 major septa reach to the outer edge of this zone of smaller dissepi- 

 ments, and are occasionally continued as thin plates into the 

 peripheral vesicular area. The minor septa form slight projections 

 into the medial area, but are irregularly and incompletely developed 

 in the dissepimental area. The major septa in a full-grown speci- 

 men number from 70 to 80. They are thickened in the medial 

 area, but taper somewhat towards their inner ends. They are 

 usually a little thicker in the neighbourhood of the fossula. There 

 is a distinct fossula, but no great break in the septa. 



Characters seen in longitudinal sections. — The tabulae 

 are numerous and somewhat close together. They are nearly flat 

 in the middle of the cylindrical corallum, and dip sharply as they 

 reach the inner wall, but more especially into the fossula. The 

 outer zone of vesicles and the inner zone of smaller dissepiments 

 are distinguishable. There is no tendency to vesicular Cyatho- 

 phylloid characters in the tabulae. 



The central area with bare tabulae usually occupies over a third 

 of the width of the corallum in the cylindrical part. The length 

 of the septa, as seen in transverse section, of course depends upon 

 the plane of section. In the young conical stages, the septa reach 

 nearly or quite to the centre of the corallum, and there is little or 

 no dissepimental zone in the very young stage. 



This species occurs abundantly in the dark limestones of the 

 western part of the district, aud much more sparingly in some of 

 the white limestones of the knolls. I have found several specimens 

 in the Elbolton Knoll and in the well-bedded limestone of the 

 Wharfe Yalley close by. In the Elbolton Limestones I have found 

 a variant which has large bubbly dissepiments. In the well-bedded 

 dark limestones the species seems to be characteristic of the middle 

 horizon of the beds exposed there. (See notes on Crag Laithe and 

 Bell Busk, and other exposures.) 



Caninia hettonensis, sp. nov. (PI. XXXIX, fig. 6.) 



This may be a variant of C. c/if/antea, Mich., but I am of opinion 

 that it deserves recognition, provisionally at any rate, as a distinct 

 species. It occurs as long coralla, often reaching 8 or 9 inches 



