MAZATLAN UNIVALVES 465 
angle below the shoulder less conspicuous than in O. angulata. 
The parietal teeth are either wanting or extremely minute ; 
and the columellar plaits are generally white ; rarely slightly 
tinted with purple or brown. The prevailing tint is as in the 
W. Indian O. reticularis, which is a much more regularly 
shaped shell. There are always a number of penciled lines 
below the suture, sometimes irregular, sometimes gathered in 
bundles or triangles. The colour-pattern shews a tendency to 
triangulation, sometimes nearly hidden by a rich layer of dark 
cloudy dots, (passing into O. angulata,) sometimes sharply 
developed. The variations in painting are so great as to 
require that a large proportion of the small stock sent should 
be retained. Long. 1°82, long. spir. °42, lat. ‘82, div. 80°. 
Hab.—Mazatlan ; very rare; L’pool Col. 
Tablet 2111 contains 2 sp., with rich, lustrous brown mark- 
ings; triangulation indistinct. —2112, 2 do. ground lighter.— 
2113, 2 do. round yellowish.—2114, 2 2 do. er acral grey. 9115, 
2 do. light, with faint markings. 
Tablet 2116 contains 2 sp., rich dark colour, triangulation 
distinet.— 2117, 2 do. ground lighter.— 2118, 2 do. ground 
orange brown.— 2119, 2 do. markings flesh coloured. — 2120, 
2 do. zigzag lines separating. 
592. OLIVA INTERTINCTA, 27. s. 
O. t. formé “O. Melchersi” simulante: sed multo minore ; 
anfr. U1. nucleosis porcellanis, apice planato ; iv. normalibus, 
spira subelevatd ; inter trientem et dimidium totius longitudinis 
obscure angulato ; spird parum callosd ; superficie albd, casta- 
neo sparsim tenue maculata, interdum lineis irregularibus con- 
Sluentibus ; labro intus ad marginem castaneo-fusco variegaté ; 
pariete denticulatd ; plicis columellaribus omnibus castaneis. 
More than a score of specimens were found agreeing in the 
above particulars, and not according with the young of any of 
the other species ; of which however it may ultimately prove 
to be a variety. It has the shape of O. Melchersi, but differs 
in the dentition of the inner lip, and in the chestnut stain on 
all the plaits, not on all but one as in O.venulata. Miss Steere, 
whose attention to this.genus is well known, has a larger 
specimen, which she had long considered as distinct : another, 
- from an unknown locality, in. my collection, confirms her judg- 
ment. Long. '78, long. spir. °2, lat. °37, div. 70°. 
