330 GASTEROPODA OF THE INFERIOR OOLITE. 
Bibliography, §c.—The author recognised a form of Onustus, occurring rarely 
at Balin and Sanka, which he regarded as occupying an intermediate position 
between O. ornatissimus, @ Orbigny, and O. papyraceus, Héb. and Desl., the latter 
representing the section of which O. pyramidatus is the type. 
Description : 
Height 5 : ‘ . 10mm. 
Width ‘ : , : 2 mm: 
Spiral angle . ; oor 
Shell short, conical, pointed. The spiral angle but slightly concave. Number 
of whorls about six. These are flat, closely fitting, and ornamented with very 
regular coste of moderate prominence, so arranged that there are about thirty in 
the body-whorl. The intercostal spaces are moderately scaly. 
Base nearly flat, but rising towards the rhomboidal aperture ; peripheral border 
slightly crenulated. There is a very faint submarginal channel, and an umbilical 
hollow rather than a true umbilicus: spiral strize of the base very distinct. 
Relations and Distribution.—Although this shell does not correspond in all 
respects with the form described by Laube, its obviously intermediate character 
between the pyramidatus-group and O. ornatissimus must be my justification 
for thus identifying it. Whilst the flanks of the shell are characteristic of O. 
pyramidatus and its allies, though with a narrower spiral angle, the spiral 
ornamentation of the base entirely removes it from this group, and brings it into 
comparison with the still stronger basal striz of the species next described. 
A single specimen from Stoford, horizon unknown. Fig. 7, representing a 
shell from the Cadomensis-bed, Oborne, may be a variety. 
264. Onustus ornatissimus, d’Orbigny, 1850. Plate XXVII, figs. 8 a, 8 b. 
1850. Trocuus ornarisstmus, d’Orbigny. Prod., i, p. 264. 
1852. = == = Terr. Jur., vol. ii, p. 272, pl. ccexii, 
figs. 5—8. 
Cf. also — — — ?, var. Ponvronts. Morris, Quart. 
Journ. Geol. Soc., vol. ix, p. 348, 
pl. xiv, fig. 10. 
Non Onvstus ornartsstuus, d’Orb., sp. Hudleston, Geol. Mag., dec. 3, vol. i, 
p- 298, pl. ix, fig. 1. 
Description : 
Height of average specimen ; ; . 10—12 mm. 
Width ‘ ; ; . . 17—19 mm. 
Spiral angle (concave) . ‘ : . 80°—85°. 
