MAZATLAN UNIVALVES 377 



on the front surface.* Labral teeth 1317, none intercalary. 

 Shape variable, ovoid or oval ; generally with thick callosity 

 on each side, and flattened face. The largest normal speci- 

 men measures long. '81, lat. '64, alt. '43. 



A rounded sp. '73, *6, '47. 



An elongated sp. "81, ,, '55, '38. 



Hob. Acapulco, Hurnboldt. Sf Bonpland. St. Elena, under 



stones, Owning. 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. TEIVIA SOLANDBI, Gray. 



Cyprsea Solandri, Sow. Conch. III. no. 128, f. 43. Rve. Conch. 



Ic. pi. 21, sp. IVZMke. in Zeit.f. Mai. 1847, p. 183, no. 30. 

 Trivia Solandri, H. fy A. Ad. Gen. i. 269. 



Distinguished normally from T. radians by smaller size, 

 redder colour, less swollen sides, rounder face with unbroken 

 lines, greater 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. '54, ,. '39, '29. 



An elongated sp. ,, *65, ,, '36, '28. 



Hob. Mazatlan ; very rare ; ISpool Col. 



Tablet 1794 contains 2 sp. approaching the dwarf form of 

 T. radians. 1795, 3 sp. normal state. 



* Desk, erroneously states that each of the rays ends in a tubercle. 



t 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 orer the base. 



