﻿CIRRUS. 



311 



A single specimen, said to be from the Oolite Marl, may fairly be regarded as a 

 member of the LeacM-groixp, but it would be going a long way in " lumping " to 

 describe it even as a variety of Cirrus Leachi. No species of Cirrus has, to my 

 knowledge, been found either in the Lincolnshire Limestone or in the beds of 

 Inferior Oolite age in Yorkshire. 



244. Cirrus pyramidalis, Tawney, 1873. Plate XNI\ r , figs. 18, 19, types refigured ; 



fig. 20, variety from the Cotteswolds. 



1873. Cirrus pyramidalis, Tawney. Dundry Gasteropoda, p. 37 (29), pi. n, 



figs. 10 a, 10 6. 



Non — — — sp., J. Buckman. Proc. Dorset N. H. 



Field Club, p. 139, pi., fig. 5. 



Description : 



Length . . . . .30 mm. 



Height of body-whorl to total length . . 40 : 100. 



Spiral angle (mean) about . . . 65°. 



Shell sinistral, turbinate, moderately umbilicated. Spiral angle concave ; 

 apex acute, but extreme apical conditions unknown. Number of whorls about 

 ten or eleven; the apical ones are nearly flat, but with the sadden increase in the 

 width of the spiral angle become convex, with a basal keel moderately developed, 

 below which the sutures have rather a tendency to gape. The ornaments consist 

 of a number of fine wavy spirals, which decussate with very numerous closely-set 

 oblique growth-lines. Rugose axial costas extend from suture to suture in the 

 earlier whorls, but fail quite to reach the anterior margin in the penult. 



The body-whorl is very ventricose, with one strong keel at the angle of the 

 whorl, which the axial costas just fail to reach. Numerous fine undulating lines 

 represent the spiral ornamentation, and one of these lines is sometimes of 

 sufficient prominence to form a slight posterior keel. The base is rounded, and 

 full of fine reticulate ornament, and the margin of the umbilicus is corrugated by 

 low radial costas not always perceptible. Aperture circular, expanding, and 

 adherent. 



Relations and Distribution. — It may be doubted whether this is anything more 

 than a local variety of the species next described. The differences are mainly 

 those of ornamentation, but in the form now under consideration the whorls are 

 less turbinate, the body-whorl is more angular, the habit of growth smaller, and 

 the spiral lines much finer and more close-set. Rare at Dundry. A variety 

 (fig. 20) occurs in the Cotteswolds. 



