TROCHOTOMA. 449 
390. TrocHoroma Lrypoyensis, sp. nov. Plate XLI, figs. 8, 8a, and 9. 
But ef. Trocuus Quineuectnetus, Zieten. Verstein. Wiirt., p- 46, pl. xxxv, 
fig. 2 (Lrochotoma quinquecincta, 
Zieten, Fischer, Man., p. 848). 
Cf. also Trochoroma catix, Phillips. Lycett, Cotteswold Hills, pl. iii, fig. 6 
(fossils of the Fimbria-stage). 
Description : 
Height : . : ; 2) Ohm: 
Basal diameter : ; : a Jil soavan. 
Spiral angle . : : eee. 
Shell thick, conical, subtabulate, and largely excavated. Spire rather obtuse 
at the apex, otherwise regular. Number of whorls five to six; these are angular 
with a narrow tabular ledge and steeply sloping flanks; sutures slightly canali- 
culate. The ornaments are sharp and conspicuous; the narrow posterior flat 
area of each whorl is marked by a strong granular spiral line between two deep 
sulci; the upper carina at the angle of the whorls is boldly prominent and somewhat 
subdivided, although there is no actual fissure-band ; there is a single spiral rather 
below the middle of the side of the whorl (fig. 8 a), and this is followed by a sort 
of double basal keel, which causes the whorls of the spire, except at the extreme 
apex, to be bicarinate. 
The body-whorl is strongly bicarinate with a very full and bluntly angular 
periphery, which is spirally striated up to the margin of the excavation. The 
loop is long and narrow. The aperture is subquadrangular, but curiously indented 
owing to the sinuous and toothed character of the columellar lip ; the outer lip is 
thin at the margin, but tcothed and grooved internally, in connection apparently 
with the loop. 
Relations and Distribution—The Lincoln shells are, in some cases, so well 
preserved as to exhibit characters which may exist in other British specimens of 
Trochotoma, but are yet obscured by the plugging of the basal cavity; hence a 
comparison with 1’. calix, for imstance, is difficult. T. Lindonensis is related to 
T’. caliz just in the opposite direction to the latter’s affinity for 7. gradus. But it 
is distinguished from 1’. calix by its more conical outline, higher spire, and narrow 
tabulation ; also by the invariable bicarination of the spire whorls, and the very 
considerable difference in the details of ornament. The specimen figured by 
Lycett as T. caliz from the Fimbria-stage of the Cotteswolds possesses some of 
the features of 7. Lindonensis, especially as regards ornament, and seems to be a 
kind of intermediate form. 
On the other hand, 7’. Lindonensis presents a strong resemblance to 7’. quinque- 
