302 GASTEROPODA OF THE INFERIOR OOLITE. 
Inferior Oolite in this country, and there occurs one species in the Upper Lias of 
Compton which may be regarded as a variety of Cirrus Leachi. This form seems 
to have been the first of the group in the British Jurassics, and its modified 
descendant, Cirrus Leachi, remained the demoid species of the Inferior Oolite. 
These would be classed under Scevola by Gemmellaro. 
Whatever generic names are assigned to these rugose sinistral Gasteropods, 
as a matter of fact in this country they nearly all occur on one horizon, viz. 
the Murchisonz-zone, and are, I suspect, pretty closely related to each other. It 
would not have been difficult, perhaps, to have folded them all under Cirrus had 
that genus been more fortunately constituted. 
Bibliography of Cirrus.—In October, 1816, Sowerby gave his diagnosis of the 
genus, laying great stress upon the funnel-shaped umbilicus. “It is a curious 
genus, and would be considered a Turbo till modern discernment showed the 
necessity of nicer distinctions ; having no columella, it represents the whorls of 
some tendrils called Cirri, or a curled lock of hair; I have therefore named it 
Cirrus.” 
The sinistral character seems to have been lightly regarded by Sowerby. 
Accordingly (¢ Min. Conch.,’ t. 141) he described, first, a dextral shell from the 
Carboniferous Limestone of Derbyshire as Cirrus acutus; this is referred by 
Morris to Hwomphalus. The second figure on the plate is that of a sinistral shell 
which Sowerby named Cirrus nodosus. This is interesting as being the first of 
the group to which I am now referring that was ever figured. The specimen was 
picked up near Yeovil, and evidently came from the Inferior Oolite of Coker, 
Stoford, or Bradford Abbas. As Sowerby subsequently described a very different 
set of shells under the title “‘ nodosus,”’ this form has been named Cirrus inter- 
medius by J. Buckman. 
In December, 1818, Sowerby (‘ Min. Conch.,’ t. 219, figs. 1, 2, and 4) 
described Cirrus nodosus, No. 2, from specimens obtained at Dundry. It is more 
than probable that two distinct species are included in these three figures. A 
very imperfectly preserved fragment of a sinistral shell (op. cit., t. 219, fig. 3) 
was described as Cirrus Leachi. 
In September, 1823, Sowerby (op. cit., tt. 428, 429) described four additional 
species of Cirrus, all dextral shells, and most probably Pleurotomarias, two being 
from the Chalk. 
Thus we perceive that the Cirrus of Sowerby, regarded as a genus, includes 
three distinct genera, viz. Cirrus as restricted to certain sinistral forms, 
Euomphalus, and Pleurotomaria. It was held to extend from the Carboniferous 
Limestone to the Chalk inclusive. It will be necessary, therefore, in adopting the 
generic name Cirrus for a group of sinistral shells occurring in the Inferior Oolite 
to reconstitute and define the genus, and to eliminate as far as possible those 
