lod 
MAZATLAN UNIVALVES 217 
Hab.—Gallapagos Is., Cuming—Mazatlan; not uncommon, 
frequently growing on uneven surfaces, and often covered 
with algx ; L’pool Col. 
Tablet 1039 contains the two youngest specimens. 
Tablet 1040 contains 3 sp. smooth growth, hole oval.—i041, 
3 do. regular form, hole with medial constriction.—1042, 3 do. 
elongated growth.—1043, 2 do. hole trilobed.—1044, 1 do. hole 
elongated, lobed at each end. 
Tablet 1045 contains 3 sp. rough growth, hole rounded oval.— 
1046, 3 do. hole elongated oval.—1047, 3 do. with mediai con- 
striction. — 1048, 4 do. hole elongated, obscurely trilobed.— 
1049, 5 do. hole sub-linear, lobed in the middle. 
Tablet 1050 contains 5 sp. ribs varying from fine and equal 
to very coarse and unequal.—1051, 3 sp. red colour developed 
outside.—1052, 7 sp. with more or less of red stains within.— 
1053, 2 sp. dark line round callus well developed.—1054, 2 sp. 
elevated growth. — 1055, 1 sp. with two large perforations 
(made by ? Lithophagi.) 
274, FISSURELLA NIGROCINCTA, 2. 8. 
“F. t. ovali, lata, conici; alba, lineis nigris radiantibus 
eleganter picta ; striis radiantibus tenue calatd ; apertura 
subcentrali, obscure trilobata ; intus alba, margine tenue crenu- 
lato, denticulis nigris ; callositate albd, lined nigré cinctd.” 
“Differs from the young of F. alba in its greater breadth, 
less compressed growth, finer strie and crenulations ; from F. 
nigropunctata, in the black line round the callosity ; and from 
both in the form of the hole, which is trilobed, not contracted 
in the middle. Long. °75, lat. °52, alt. °3.” 
Proc. Zool. Soc. Dee. 1855. 
Hab.—Mazatlan, Mus. Cuming.—?Do.; extremely rare, on 
Spondylus caleifer ; L’pool Col. 
Tablet 1056 contains one of two very young specimens ‘07 in 
length, which may belong to the above species, described from 
specimens in the Cumingian Collection. Although so small, it 
displays no trace of spiral vertex. Shell white, with black 
stripes. Hole suboval: this may be a character of youth. 
275. FissuRELLA,————, sp. ind. 
Shell elongated, conic, much compressed; ribbed as in F, 
virescens, &c.; anterior side shortened; hole long, narrow, 
trilobed ; colour green within, nigropunctate at the margin ; 
May 1856. v 
