S576 MAZATLAN UNIVALVES 
the top and bottom of the back. The pustules are almost 
always of a rich reddish orange, witha ring of dark at the 
base. The dorsal line is scarcely indented, but is free from 
pustules. The front ribs are often continued faintly over the 
sides. Shape oval or produced, with beaks more or less 
prominent. Labral teeth about 18 ; sometimes these are 
formed by principal ribs; sometimes by fainter intercalary 
ones, as in T. Solandri; sometimes there are marginal inter- 
ealations. Pustules very variable in number; two dwarf 
specimens have 94 and 176 respectively. Columellar excava- 
tion long and deep, bounded externally by a sharp rib. The 
smallest adult spectmen measures Jong. ‘51, lat. *3, alt. 21. 
The largest do. Se OSs eG, LB as 
A broad sp. oY Cio. 2 Ue: te. 
An elongated sp. Onc arn. ek 
Hab.— Mexico, Humboldt & Bonpland.— Panama and Isl. 
Plata, [mear Cape San Lorenzo, lat. 1°6°| under large 
stones, at extreme low water mark of spring tides only, rare ; 
C. B. Adams.—S. W. Mexico, P. P. C.—Mazatlan; L’pool 
vol. 
Tablet 1781 contains 7 sp. in different stages of growth.— 
1782, 7 sp. white conspicuous.—1783, 7 sp. pustules few, large.— 
1784, 7 sp. usual state—1785, 7 sp. pustules small, crowded.— 
1786, 3 sp. broad form.—1787, 3 do. elongated form.—1788, 
2 sp. ashy tint, pustules searcely bordered.—1789, 2 sp. shew- 
ing extremes of size.—1790, 2 dwarf sp. shewing extremes of 
shape and markings. 
140. Trivia Rapians, Lam. 
Cyprea radians, Lam. Ann. Mus. vol. xvi. p..102, no. 62 :— 
An. s. Vert. vol. x. p. 540, no. 62.—Gray Zool. Journ. vol. ii. 
p. 364.—Val. in Humbh. Rec. Obs. vol. ii. p. 335.—Pot. & 
Mich. Moll. Mus. Douai, vol. i. p. 485.—Sow. Conch. Ill. 
pl. 119, f. 146.— Rve. Conch. Syst. pl. 286, f. 146 :— Conch. Te. 
pl. .f.117—Kien. Icon. Conch. p. 129, pl. 23, f.3.—C. B. 
Ad. Pan. Shells, p. 37, no. 10. 
Cyprea oniscus, Wood Ind. Test. pl. 17, f. 58, (err. typ.)—Non 
C. oniseus, Lam. An. s. Vert. vol. x. p. 540, no. 63 :—Dillw. 
Deser. Cat. p. 466, no. 61 :—v. Desh. in loc. 
Trivia radians, Gray Descr. Cat. p. 16, no. 137. 
Most of the Mazatlan specimens were dead; but when fresh, 
it is of a brownish colour, with some of the lines interrupted 
