380 GASTEROPODA OF THE INFERIOR OOLITE. 
317. Trocuus moniuitectus, Phillips, 1829. Plate XXXII, figs. 3a, 30. 
1829 and1835. Trocuus MonriLirectus, Bean, MS. Phillips, Geol. Yorks., pt. 1, p. 152 
(8rd edit., p. 259), pl. ix, fig. 33. 
1850. — — Phil. dOrbigny, Prod., 1, p. 265. 
1851. —_ = — Morris and Lycett, Great Ool. Moll., pt. 1, 
p. 116, pl. xv, fig. 1. 
1885. — — —  Haudleston, Geol. Mag., dec. 3, vol. ii, 
p- 121, pl. iii, figs. 1, La, 14. 
Cf. also —  Brurvs, d’Orbigny. Terr. Jur., vol. ii, p. 283, pl. ecexv, 
figs. 13—16. 
~ — — Cossmann, Etage Bath., p. 285, pl. vii, 
figs. 23—24. 
Bibliography, §c.—This little shell is a genuine representative of the section 
Zizyphinus, and belongs to a group completely conical in outline, the result of flat 
whorls and a close suture. In the Bathonian of France Trochus Zenobius, d’Orb., 
seems to represent it. T'vrochus Brutus, which has a wider spiral angle, is stated by 
M. Cossmann, on the authority of Schlumberger, to be common in the Bajocian, 
I presume of eastern France. 
Description —Typical form from the Scarborough Limestone of Cloughton 
Wyke : 
Height : ; é 2 oO mam. 
Width : . : s =) Comm. 
Spiralangle . 5 : =, 607 
Shell regularly conical, imperforate ; spire acute, and nearly two-thirds the 
total height. Whorls flat, suture extremely close. The ornaments consist of 
four, and sometimes five equal spiral bands, which are close together and evenly 
tuberculated, the tubercles or granules being nearly circular. 
The body-whorl has four tuberculated spirals, together with a thicker belt, 
constituting the basal periphery. Base flat with faint spiral striz towards the 
margin (not always visible), the rest smooth or only marked by faint radial lines. 
Aperture rhomboidal and depressed. 
Relations and Distribution.—The typical 7. monilitectus seems almost confined 
to the Scarborough Limestone and to the Upper Beds of the Lincolnshire 
Limestone, especially at Ponton, where its presence was first recorded by Morris 
in 1853 (¢ Quart. Journ. Geol. Soc.,’ vol. ix, p. 326). 
Further south, e.g. in the Parkinsoni-zone of Aston, Notgrove, and Horton Hill, 
and also at Grove, near Castle Cary in Somersetshire, there occurs a larger form 
with five or six nodular spirals (see fig. 4). The greater number of spirals is often 
