MM. Wilson and Crick—The Lias Marlstone of Tilton. 301 
ornamentation Purpurina Patroclus, D’Orb., is remarkably like, and 
is probably related to, the type of Mr. Hudleston’s new Jurassic genus 
Pseudalaria (Alaria) Etheridgi, Tawney, but the characters of the 
aperture are sufficiently different in these two shells to bring them 
under distinct generic groups. I believe it will be best to found 
a new genus for the reception of this remarkable Rutland fossil. I 
therefore, suggest for it the name Nortonia, in reference to the only 
British locality, Hast Norton, where it has at present been found. 
Nortonia might be briefly defined as a Cerithium with a very 
shallow anterior canal, and with eucycloid spire and ornamentation.’ 
Nortonia Patroclus is perhaps one of those “common forms” which 
serve to link together several very diverse genera, such for example 
as Cerithium and Pseudalaria on the one hand, and Amberleya and 
Purpurina on the other. 
I am indebted to Mr. Beeby Thompson, F.G.8., of Northampton, 
for the opportunity of examining this extremely interesting fossil. 
Geological Horizon and Locality.n—Upper Lias Shales, Railway- 
cutting, Hast Norton, Rutland. 
Crrituium (CERITHINELLA?) conFusum, Tate, 1875. Plate IX. 
Figs. 2, 2a. 
1875. Cerithium confuswm, Tate, Gzou. Maa. Dee. II. Vol. II. p. 2065. 
I have several specimens of a highly elongate conical shell from 
East Norton, which answers to the description given by Tate of the 
above type. The state of preservation of these fossils is not suffi- 
ciently good to indicate with certainty their generic position. No 
figure accompanied the original description. I therefore give illus- 
trations from our Leicestershire specimens. 
Marlstone Rock, Tilton (Hast Norton embankment). 
CrERITHIUM FERREUM, Tate, 1875. Plate IX. Figs. 3a, 3b, 3e. 
1875. Cerithiwm ferreum, Tate, Grou. Mac. Dec. II. Vol. II. p. 205. 
A number of shells have been obtained from the Marlstone Tran- 
sition-bed of Tilton, and from the East Norton embankment, which 
correspond with Tate’s type. No figures of this form having yet 
been published, I give illustrations from Tilton specimens to supple- 
ment the original description in the GronocicaAL MaGazInE. 
Marlstone Rock, Tilton (Hast Norton embankment and Tilton). 
CrriTHiumM costunatumM? Desl. 1842. Plate IX. Figs. 4, 4a. 
1842. Cerithiwm costulatum, Desl. Mém. Soc. Linn. Norm. vol. vii. p. 199, 
pl. xi. figs. 12, 13. 
There is a single imperfect specimen from Hast Norton, of an 
elongate conical shell, which appears to represent the above type of 
As a general principle, no doubt, it is not safe to found a genus or even a species 
on a single specimen, and this prevents my giving a more precise diagnosis of 
Nortonia. In justification of the aboye genus-making however, it may be said, 
that the characters of N. Patroclus are exceedingly well defined, that our solitary 
specimen is apparently an adult shell, and is exceptionally well preserved, and that 
there is evidence of its maintaining its characters constant over a wide geographical 
area. 
