* 
9S 
TROCHUS similus, 
TAB. CXLIL 
Spec. Char. Conical, base rather convex, volu- 
tions squarish, with tubercles upon their angles, 
transversely earinato-striate, and a round- 
ing 1 elevation in their centers ; lines of growth 
decussating the three central striae 
The tubercles are numerous, rather depressed, but 
large, the striae are undulated and pass over them ; be- 
tween the three central striae which lie upon the elevated 
part of the whorls the lines of growth are seen very 
sharp, close and regularly arched : the columella is im- 
perforate, and the interior of the shell is nearly plain, 
retaining but small signs of the tubercles : the aperture 
is square with rounded angles, and the inner lip is thick- 
ened, two characters not well expressed in the figure, 
which was taken from a handsome, but in this respect an 
imperfect specimen. 
The Blue Lias at Weston near Bath, and in the neigh- 
bourhood of Yeovil, Lackington Park, Shotover, &c. 
abounds with this Trochus. Lister found it at Bugthorp, 
Yorkshire, and has figured it in his Conchology, f. 1036 . 
It is found of considerable size, and more or less worn 
so as to disguise it in a way that makes it often difficult 
to distinguish the species. When most perfect it is very 
much ornamented with transverse undulating striae, and 
often a rather conspicuous sort of belt, which has what 
some have occasionally denominated a herring bone 
marking. Among my specimens are several casts of the 
interior only ; some are included in a mould of the outer 
surface, like the lower figure ; and the space between 
