310 GASTEROPODA OF THE INFERIOR OOLITE. 
turriting, and ornamented by spirals decussating with numerous closely set axial 
lines. In the last three or four whorls of the spire the ornamentation becomes 
very rugose, but with considerable differences of development. ‘The anterior half 
of the whorls is occupied by two keels, of which the upper one is grossly tuber- 
culated ; the lower keel is sometimes tuberculated, sometimes it is little more than 
a serrated band (as in CO. gradatus). Axial ribbing extremely coarse and rather 
wide apart. In well-preserved specimens a system of reticulation between fine 
intermediate spirals and the oblique growth-lines may be seen. In specimens 
from Coker this feature is rarely preserved. 
The body-whorl is largely ventricose, subangular, and rugosely bicarinate, but 
there are considerable differences ; specimens from Dundry have a rounder and 
still more ventricose body-whorl, with ornamentation so irregular that the spiral 
is often overpowered by thick tubercular axial coste. The base is full, sub- 
angular or rounded, and strongly costated; the umbilicus varies considerably in 
width and depth. Aperture circular, expanding somewhat, and adherent. 
Relations and Distribution.—There is a strong temptation to make several 
species out of Cirrus Leachi, and indeed one might fill a quarto plate with figures 
of varieties. Firstly, we have— 
a. The very wide angled and coarsely costate form with bicarinate and 
angular whorls from the bifrons-beds of Compton, which was figured by Moore ; 
the ornamentation somewhat resembles that of Turbo Hérnesi, Stol., but the 
Compton fossils have a much wider spiral angle, and are umbilicated. 
b. The prevailing form at Coker and elsewhere in the Murchisonx-zone of 
Dorset is not unlike that of the Compton fossils, but the ornaments are not quite 
so rugose, and the spire is rather higher. This variety was well figured by 
J. Buckman. Fig. 3 of the accompanying plate represents a somewhat less 
angular form of this variety. 
c. There is a smaller and somewhat less ventricose variety with finer and 
closer coste from Bradford Abbas (see fig. 5). 
d. Specimens from Dundry, in the Bristol Museum, are extremely ventricose, 
the body-whorl being both wide and high, and the bicarinate character becomes 
almost obliterated by rugose axial ornamentation. To a certain extent this 
variety is represented by Cirrus Fourneti, Dum. I am somewhat inclined to 
classify the very elegant specimen from Bradford Abbas, fig. 4, with this section. 
In this particular specimen the umbilicus is so restricted that I have distinguished 
it in my Collection as var. ‘* subumbilicata.” 
Cirrus Leachi abounds at Coker and Stoford, but is not very common at 
Bradford Abbas. Fine specimens were formerly obtained at Dundry. One 
would expect some modification of the demoid species of Cirrus to occur in the 
Cotteswolds, but at present I am without reliable information on this point. 
