MAZATLAN UNIVALVES 271 
A long decked sp., margin to front °36, to back *47. 
A short do. By ASA S88! 
Hab.—(C. aculeata) W. Indies, passim, auect.—Cuba, Sagra.— 
Honduras, Dyson.—Brazils: Patagonia; D’ Orbigny.—Ben- 
guela; 1 sp. in excellent preservation; Zams.—Table Bay, 
Krauss—Cape Natal, Mus. Cuming.—Isle of France, Hav- 
anne.—Kurachee, Mouth of the Indus, Mus. Cuming.— Port 
Jackson, Rev. R. L. King.—New Zealand, Rev. R. Taylor.— 
Sydney and Swan River, Mus. Cuming.—(Dark var.) Japan, 
Mus. Cuming.—(Light var.) Chil, Capt. Ld. Byron.—(€. 
echinus, &c.) Lobos Is. Peru, Cuming.—Panama; under stones 
at low water, rare ; C. B. Adams.—(C. Californica) Monterey, 
common, Nuttall.— Mazatlan ; common, on shells &e. ; 
young shells abundant on Chame and Spondyli; L’pool Col. 
Tablet 1321 contains 10 sp. extremely young.—1822, 7 do. a 
stage older, with a fragment to shew the inner surface of the 
deck.—1323, a young deformed shell, nearly smooth, probably 
belonging to this species. 
Specimens illustrating form and sculpture.—Tablet 1324 con- 
tains 8 sp. (var. hystrix) of different ages.—1325, 13 sp. do. 
(var. echinus.)—1326, 8 sp. do. finely aculeate, arched.—1327, 
10 sp. do. flat, (one of the young in situ on an adult.)—1328, 8 
sp. do. spiny processes ‘imperfectly developed.—1329, 4 sp. do. 
(var. Californica.)—1330, a series of 12 sp. shewing gradations 
between the above forms.—1331, 7 sp. shewing gradations from 
flat to arched.—1332, 6 sp. shewing gradations in amount of 
spiral involution.—1333, 5 sp. shewing gradations in size of 
deck.—1334, 6 sp. shewing gradations in prominence or sinking 
of deck. 
Specimens shewing shape of deck.—Tablet 1335 contains 3 sp. 
center pointed, sides much swollen.—1336, 4 do. sides swollen. 
— 1337, 3 do. sides slightly swollen. — 1338, 3 do. center 
rounded.—1339, 1 do. point turned outwards.—1340, 4 do. form 
approaching C. nivea.—1341, 3 do. deck partially opaque. 
Specimens displaying changes of colour.—Tablet 1342 contains 
2 sp. (hystrix and echinus) pure white.—1343, 10 sp. variously 
shading into brown.—1344, 11 sp. do. dark lustrous brown.— 
1345, 12 sp. tortoiseshell, variously mottled.—1346, 5 do. whiter 
tint.—1347, 6 do. more or less tinged with green. 
Distorted specimens.—Tablet 1348 contains 7 sp. of irregular 
shape.—1349, 7 sp. diseased by worms.—1350, 3 sp. with addi- 
tional margin.—1351, 4 sp. passing towards C. nivea.—1352, 3 
sp. passing towards C. onyx. 
