388 GASTEROPODA OF THE INFERIOR OOLITE. 
by axial lines. Base rounded and similarly ornamented. Aperture subquadrate 
with a columellar furrow. 
Relations and Distribution.—An increase in the strength of the axial orna- 
mentation would approximate this form to Trochus Niortensis. 
T. marga is most abundant in the Parkinsoni-marl at Bradford Abbas. It 
occurs more rarely on the same horizon at Burton Bradstock. 
328. Trocuus Niorrensis, d’Orbigny, 1852. 
1852. Trocuus Nrorrensis, d’Orbigny. Terr. Jur., vol. ii, p. 282, pl. eccxv, 
figs. 5—8. 
1873. — — — Tawney, Dundry Gasteropoda, p. 33 (25). 
When Mr. Tawney wrote, there were in the Bristol Museum two specimens 
from Dundry agreeing precisely with d’Orbigny’s description. A third specimen 
has since been added. Mr. Wilson, the present curator, informs me that this 
species ranges up from the Middle Lias. The micromorph from the Pea-grit of 
Leckhampton (Pl. XXXII, figs. 18 a, 18 b) is related. .N.B.—The whorls of this 
small shell are more concave than is shown in the enlargement. 
329. Trocuus, species or variety. Plate XXXII, fig. 16. 
A small, unornamented Trochus, with whorls very much undercut, occurs 
sparingly at Weldon in the Lincolnshire Limestone. In my Collection this is 
designated Trochus ** subimbricatus.” 
330. Trocuus cf. Brxa, d’Orbigny, 1850. Plate XXXII, fig. 17; and ? Plate XXXI, 
fig. 16. 
1850. Trocuus Brxa, d’Orbigny. Prod., 1, p. 800. 
1852. — — = Terr. Jur., vol. ii, p. 287, pl. ceexvi, figs. 13—16. 
Cf. also —  lLaneruyensts, d’Orb. Cossmann, Etage Bath., p. 289, pl. xiii, 
figs. 24—25. 
Bibliography, §c.—Specimens from our Inferior Oolite agree so well with the 
description and figures of d’Orbigny of a shell from the Bathonian of Luc in 
Calvados that I do not feel justified in separating them, notwithstanding the 
difference in geological age. M. Cossmann regards 7’. Biva, d’Orb., as merely a 
synonym of 7. Langrunensis, d’Orb.; but as our shells resemble 7. Bixa I retain 
the former name, the more so since the essential feature of spiral striation is 
entirely wanting in 7’. Langrunensis—possibly from attrition. 
