268 
GASTEROPODA OF THE INFERIOR OOLITE. 
ing limestone at North Luffenham (Rutland). Remains of spiral ornamentation 
decussating with growth-lines are very conspicuous on portions of the sloping 
ledge or shoulder of the body-whorl. This suggests a kind of ornamentation not 
dissimilar to that of Sigaretus. 
Relations and Distribution. — The tabulate character of the whorls and step- 
like spire serve to connect this species with Euspira. Probably Euspira canalicu~ 
lata must be regarded as its nearest relative. The low spire, wide ledge and 
angular, yet tumid body-whorl are points of resemblance. On the other hand 
the ledge or shoulder, instead of being canaliculate, slopes outwards, the spiral 
angle is considerably wider, and the habit of the species much larger. Indeed 
the great size of Natica cincta, in view of the fact that all other Inferior Oolite 
Naticas in this country are of modest dimensions, is a phenomenon of much 
interest, which becomes emphasised by the fact that this big shell appears entirely 
confined to the horizon of the Oolite Marl and its equivalents. 
Commencing in the north, this species, as we have seen, was first noticed in the 
Inferior Oolite Limestone of the Castle Howard district, which is generally 
admitted to be on the horizon of the Lincolnshire Limestone. Casts are abun- 
dant in the lower part of the latter series, though the connection of these 
corkscrew-like forms with Natica cincta is not always so evident, until we bear in 
mind the enormous thickness of this shell, especially in the umbilical region. 
Natica cincta is not found in the upper beds of the Lincolnshire Limestone at 
Weldon and Great Ponton. The best specimens are from Coombe Hill near 
Deddington (North Oxfordshire), where it occurs with Ammonites Murchisonse, 
Terebratula fimbria, and Spiropora straminea} The next place where we meet 
with Natica cincta in any quantity is in the railway -cutting through the Oolite 
Marl at Notgrove (between Bourton and Cheltenham). In specimens from this 
locality a considerable portion of the shell is apt to remain on the spire, so that 
we rarely get the corkscrew-like forms which are characteristic of the Lincolnshire 
Limestone at Denton and elsewhere. The casts which suggested the name 
LechJiamptonensis were most likely from the Oolite Marl of the Cotteswold 
escarpment. The shell quoted by Witchell (‘ Geology of Stroud,’ p. 50) from 
the Oolite Marl as Natica macrostoma, Rom., is most probably Natica cincta. 
No such species as Natica cincta has yet been discovered in Dorsetshire, but 
the form described by me as N. adducta var. globata (PI. XX, fig. 5) presents 
some points of resemblance. 
^ Judd, ‘ Geology of Eutland,’ pp. 25 — 27. 
