TROCHUS. 381 
associated with a slight basal carina which breaks the uniformity of the cone, and 
thus we gradually pass to another species. In my own Collection these are 
marked var. “‘ nemoralis.”” It is quite possible that they are undeveloped forms of 
Trochus substrigosus, described below. For similar forms see ‘ Geol. Mag.’ vol. cit., 
pl. ii. 
318. TRocHUS SUBLUCIENSIS, sp. nov. Plate XXXII, figs. 6 and 7. 
Description (full size) : 
Height : ‘ ; , . 14mm. 
Width : ; ; : . 10 mm. 
Spiral angle . : ; 40°—45°. 
Shell regularly conical, not umbilicate. Spire acute, about two-thirds the total 
height. Number of whorls about seven, perfectly flat, and increasing with complete 
regularity ; sutures close. The ornaments consist of four thick, tuberculated 
spirals, each tubercle presenting a squamous appearance, owing to a crescent- 
shaped hollow on the anterior side. 
In the body-whorl the number of these squamous spirals increases to five and 
even more; the anterior spiral is usually deflected away from the base, which is 
flat and without ornament. Aperture rhomboidal and much depressed. 
Relations and Distribution.—It is extremely probable that there is more than 
one species amongst these narrow-angled and squamously-ornamented shells, but 
the state of preservation is scarcely favorable for close discrimination. The spiral 
angle accords with that of Trochus Luciensis, VOrb.; but in that species the 
spirals are simply nodular, and do not appear to assume the peculiar rope-like 
character, which enables one to recognise even a fragment of Tvochus subluciensis. 
These shells are characteristic of the Murchisonx-zone, occurring in the 
Oolite Marl of Nailsworth, and in the Murchisonx-zone at Stoford and Bradford 
Abbas ; also on the same horizon in the Irony Nodule-bed at Burton Bradstock. 
A modified form is found in the ‘‘ Base-bed ” at Lincoln, which is also in the 
Murchisone-zone. With reference to the Gasteropoda in this bed, it may be 
observed that their tendency to vary in the direction of bizarre forms is noteworthy. 
Whether Trochus squamosior, next described, is a species or a “ sport’’ must be 
left an open question. 
