TURBO (MONODONTA). 357 
towards the anterior extremity, so as to produce a denticulated appearance 
succeeded by a kind of notch. 
Relations and Distribution.—Although there is much in this curious little shell 
to remind one of Brachytrema, I think we must regard it as a member of the 
Turbinide. The form (fig. 18) may represent an aged specimen, or possibly 
another species. It bears some resemblance to Monodonta exigua, Lycett (¢ Suppl.” 
p- 22, pl. xliv, fig. 29), from the Great Oolite. 
Monodonta pisolitica is fairly plentiful in the Pea-grit at Leckhampton. 
292. Monoponta Lyetut, d’Archiac, 1843. Plate XXX, figs. 1 and 2; var. 
humilis, fig. 3. 
1843. Monoponta Lye, d’Archiac. Mém. Soc. Géol. France, vol. v, pt. 2, 
p- 380, pl. xxix, figs. 8 and 8a; id., 
var., 8b, 8e. 
1850. Turso Lyrtu, d’Orb. Prod., i, p. 301. 
1851. Monoponva Lyenutt, d’ Arch. Morris and Lycett, Great Ool. Moll., pt. 1, 
p- 67, pl. xi, fig. 4. 
1853. — — —- Morris, Quart. Journ. Geol. Soc., vol. ix, 
p- 326. 
1884. — Lyewut, d’Arch. Cossmann, Htage Bath., p. 271, pl. vii, 
figs. 28, 29. 
Bibliography, §c.— We have the authority of Morris as to the occurrence of 
this well-known Bathonian species in the Lincolnshire Limestone, where the forms 
differ somewhat from those in the Great Oolite of Minchinhampton, and possibly 
still more from d’Archiac’s types. It seems to be an eastern form, being quoted 
from the Bathonian and Bajocian of Hastern France. 
Description : 
Height of average specimen : : a ey aeail, 
Width 4 : : . 7mm. 
Mean spiral angle : ‘ ; ay ox 
Shell turbinate, subumbilicate ; spiral angle fairly regular, but with a flattened 
apex ; sutures wide and canaliculate. Number of whorls four, the two at the apex 
smooth, the other two ornamented with from three to four tuberculated spirals, 
the tubercles having a shallow concave pit on the anterior side. 
The body-whorl is subventricose, more or less carinated, and carries three 
strongly tuberculated spirals on the side, and a fourth, with lesser tuberculations, 
at the angle. Four more tuberculated spirals ornament the base, including the 
umbilical cavity, the margin of which is fringed by the one carrying the strongest 
46 
