350 MAZATLAN UNIVALVES 
very much more common than L. aspera at Mazatlan; very 
young specimens of the latter being so rare that I am unable 
to state their exact difference, and some in each series may be 
wrongly placed. The ordinary specimens however are dis- 
tinguished by the flattened form, and faint sculpture. The 
adults have a very different aspect from each other, although 
worn specimens may be confounded. It presents less variation 
of form than either of the other species; making up for this 
by the multiform patterns of the stripes. The operculum 
closely resembles that of L. aspera; but appears to differ in 
being more transparent, with the shagreening on the muscular 
scar less and the spiral striz more conspicuous, and the nucleus 
less raised and displaying the spiral element. The ordinary 
size is ‘4, by ‘28; the smallest is ‘18 by *12; an extraordinarily 
large one measures long. °6, long. spir. °3, lat. °35, div. 50°. 
Hab.—Mazatlan ; common ; L’pool §& Havre Coll. 
Tablet 1671 contains 7 sp. ventricose, resembling the young 
of L. aspera.—1672, 8 sp. highly coloured, as in L. aspera, jun., 
but of normal shape: in the youngest, the stripes coalesce and 
nearly cover the shell. 
Tablet 1673 contains 7 sp. stripes broad, zig-zag.—1674, 8 do. 
stripes narrower, hue olivaceous.—1675, 8 do. stripes inter- 
rupted in the middle.—1676, 7 do. stripes zig-zag at base.— 
1677, 7 sp. lines very fine, olivaceous.—1678, 7 sp. stripes not 
interrupted, broad.—1679, 7 do. narrower.—l680, 7 do. very 
narrow.—1681, 7 do. olivaceous.—1682, 5 do. stripes broken-up 
into tesselations.— 1683, 6 do. markings extremely faint.— 
1684, 7 sp. spire elevated.—1685, 9 separate opercula (others 
in the shells.) 
399. Lirortna ————, sp. ind. 
Tablet 1686 contains 2 sp., one young and fresh, the other 
adult and dead, differing from the rest in colour, which is of a 
nearly uniform blackish brown, with faint spiral lines of white ; 
in texture, which is nearly smooth, with a very few extremely 
faint spiral lines near the base ; and in the columella, which is 
not excavated. Long. °5, long. spir. °25, lat. ‘32, div. 50°. 
Hab.—Mazatlan ; extremely rare; L’pool Col. 
The same tablet also contains a very young shell, measuring 
‘O7 by ‘05, more obtuse than the young of the other species. 
