MAZATLAN UNIVALVES 377 
on the front surface.* Labral teeth 13—17, none intercalary. 
Shape variable, ovoid or oval; generally with thick callosity 
on each side, and flattened face. The largest normal speci- 
men measures long. 84, lat. 64, alt. °43. 
A rounded sp. Sih Shee, “OR ge Same 
An elongated sp. J Oe 255: OP ae 
Hab.—Acapulco, Humboldt. & Bonpland.—St. Elena, under 
stones, Cuming.—Panama, extremely rare, C. B. Adams.— 
Mazatlan ; very rare living; L’pool Col. 
Tablet 1791 contains 2 sp. adolescent, ribs forming ; 1 adult, 
very fresh; 1 do. teeth close as in T. Solandri; and 1 sp. 
broken in two, shewing inner lips. —1792, the 3 sp. above 
measured.—1793, 3 sp. dwarf form, resembling T. Solandri. 
441. Trivia Sonanpri, Gray. 
Cyprea Solanari, Sow. Conch. Ill. no. 128, f. 43.—Rve. Conch. 
Ic. pl. 21, sp. 113.—Mke. in Zeit. f. Mal. 1847, p. 183, no. 30. 
Trivia Solandri, H. & A. Ad. Gen. 1. 269. 
Distinguished normally from T. radians by smaller size, 
redder colour, less swollen sides, rounder face with unbroken 
lines, gréater excavation of the columella, and the presence of 
2—4, intercalary teeth in the labrum,t the whole number 
varying from 15—18. An examination of at least 150 specimens 
of this species and T. radians has not confirmed the impression 
of distinctness which is given by extreme forms. The last is 
the only reliable character, and even that is varying; so that 
some specimens of T. radians have more teeth than others of 
T. Solandri. The arrangement of ribs in each form is too 
uncertain to found specific marks upon them. An examination 
of the animals, or at least of several hundred fresh specimens 
from different localities, appears needful to decide the point. 
The largest of the specimens, with only two intercalary teeth, 
measures long. 63, lat. 44. alt. 35. 
A rounded sp. ee a Aes A PGS. SS ee 
An elongated sp. ear Bae SG. ssi ee 
Hab.—Mazatlan ; very rare; L’pool Col. 
Tablet 1794 contains 2 sp. approaching the dwarf form of 
T. radians.—1795, 3 sp. normal state. 
* Desh. erroneously states that each of the rays ends in a tubercle. 
+ Reeve states that there is ‘‘an intermediate tooth between each of those 
terminating the ribs.”’ In the Mazatlan specimens, I have never seen more than 
4, generally 2 or 3; these moreover are not teeth, but rudimentary ribs, con- 
tinued for some little distance over the base. 
