316 GASTEROPODA OF THE INFERIOR OOLITE. 
flattened at the periphery, but more or less pinched in anteriorly, usually provided 
with two tubereulated marginal keels. Aperture quadrangular. 
As a rule in the species referred to Straparollus, the shell, even when there is 
no salience of the spire, is proportionately higher than in Discoheliz. All the 
forms are rare. 
248. DisconzLix Corswoipia, Lycett, 1850. Plate XXV, fig. 7. 
1850. Sonartum Corswoupim, Lycett. Ann. Mag. Nat. Hist., 2nd ser., vol. vi, 
p- 419, pl. xi, fig. 2. 
1853. — = — Proc. Cotteswold Nat. Club, vol. i, 
p. 80, pl. ii, fig. 2. 
1854. — — sp. Morris. Catalogue, p. 279. 
1857. — — Lycett. Cotteswold Hills, p. 40. 
Description : 
Diameter (large size) . , . . 12mm. 
Height 5 é : ; . 4mm. 
Shell discoidal, depressed, upper and under surfaces nearly equally excavated, 
but there is some difference in this respect, and also in the relative height of the 
specimens. Diameter ranges from 6 to 12 mm. The sides of the whorls are 
rather flattened, but having the margins rounded off; these latter are furnished 
both on the upper and under surface with numerous nodules of moderate size, 
rather close together. The smaller specimens show richer ornamentation than 
the larger ones, and in some specimens (like the one figured) there is a tendency 
for the nodes to die out towards the aperture. 
All the whorls are ornamented by fine wavy spiral lines, and in the body- 
whorl this feature prevails both above and below and on the flank. Aperture 
quadrangular, spiral and axial diameters nearly equal. 
Relations and Distribution.—There is considerable variety in the shells referred 
to Discohelix Cotswoldiz. Moreover, in many instances, the specimens are by no 
means well preserved. Consequently we may in fact be dealing with more than 
one species. Morris suggested that Solarium Cotswoldie might be identical with 
Kuomphalus tuberculosus, Thorent; but the differences are very considerable, as 
may be seen further on. Doubtless most of these forms are merely local varieties 
of some other form, but, on the whole, Discohelix Cotswoldiz is sufficiently distinct 
from anything hitherto described to be entitled to rank as a separate species. 
It occurs chiefly in the Oolite-Marl and Freestones of the Nailsworth district. 
T have small specimens from Crickley. Lycett also quotes it from Leckhampton. 
