. 
MAZATLAN UNIVALVES 347 
brown ; (not with red as in the Sitcha analogue, C. modesta ; 
which it so greatly resembles in general form that Mke. not 
unnaturally mistook them, but which is put in another sub- 
generic group by Messrs. Adams.) The shape varies from a 
type even more inflated than L. puncticulata, Phil. to one 
more elevated than his L. conspersa, with every gradation 
between. ‘The surface is either sculptured with prominent 
(though not sharp) ribs, with very broad interstices ; or with 
smaller and very close ribs, with narrow interstices: or else 
the interstices degenerate into fine lines cut on the smooth 
surface of the shell, which is then somewhat glossy; or (in 
the young state) it is quite smooth and polished. The columella 
is much excavated, even in young shells. The mouth is gene- 
rally of a rich, lustrous brown within, more or less in bands, 
with dots inside the labrum; but sometimes it has only the 
yellow of the exterior more developed. The nuclear whirls 
are of a purplish brown, (sometimes light) of chalcedonic tex- 
ture as in T’erebra, and very rarely eroded. The operculum is 
very regular in growth, with the spire well defined; outside 
with very irregular lines of growth; inside with the muscular 
scar beautifully striated spirally. This can be seen by trans- 
mitied light, and at once separates it from the next species. 
The young shell is frequently angulated at the base; and an 
unusually iarge rib often marks the periphery in the adult. A 
swollen sp. measures long. °6, long. spir. °24, lat. °46, div. 80°. 
An elongated sp. RLS ies . BTS. so: SO DOL 
Hab.—Real Llejos, Hinds—Taboga and Panama; common, 
chiefly on large fragments of rock af high water mark; 
C. B. Adams.—Mazatlan; extremely common; L’pool ¥ 
Havre Coll. 
Tablet 1638 contains £°- white, very ventricose.—1639, 9 
do. rather less, (answerfmg to L. puncticulata.)—1640, 7 do. 
ordinary state.—1641, 7 do. flattened ribs.—1642, 7 do. more 
elevated.—1643, 8 do. form L. conspersa, Phil. 
Tablet 1644 contains 7 sp. very much elevated, yellowish.— 
1645, 11 do. series from young state ‘18 by °17.— 1646, 6 do. 
less elevated. — 1647, 8 do. whirls rounded.—1648, 7 do. usual 
shape.—1649, 7 do. rather flatter.—1650, 7 do. ventricose. 
Tablet 1651 contains 3 sp. keels distant.—1652, 4 do. keels 
very close.—1653, 3 do. keels somewhat irregular, as in Purpura 
lapillus.—1654, 4: do. nearly smooth. — 1655, 4 sp. abnormal 
growth.—Many of the above retain their opercula: tablet 1656 
contains 9 separate ones. 
