NO. 1704. A COLLECTION OF fiHELLf^ FROM PERU— BALL. 169 



Shell large, rude, with spiral imbricated sculpture, the spire so 

 reduced that the last whorl appears like a lari:;e rounded limpet; the 

 color brownish. Inside white, polished, the margin more or less crenu- 

 lated, and produced toward the anterior edge into two or more pro- 

 jecting denticulations. There is an operculum, but too small to close 

 the aperture, into which the animal can barely withdraw. The shell 

 may reach a length of 80 mm. or even more. It lives seated on rocks 

 like a limpet, though closely related to the genus Thais. 



Mr. Coker in his notes mentions that this species is sometimes eaten, 

 but not esteemed. 



THAIS CHOCOLATA Duclos. 



Plate 22, fig. 2. 



Purpura chocolata Duclos, Ann. Sri. Nat., vol. 26, 1832, p. 108, pi. 2, fig. 7. 

 Caracoles. Callao Bay, shore to 2h fathoms, and on the shore of San Lorenzo Island. 

 This form is commonly sold in the markets, after being removed from the shell. 



Distribution. — From Valparaiso, Chile, northward to Paita, Peru. 



Shell large, solid, with a short spire and very large body whorl often 

 carinated and more or less tuberculate at the shoulder of the whorl; 

 exterior chocolate color, the aperture within bluish or yellowish, the 

 pillar orange colored; the shell when weathered, as many specimens 

 are, becomes of a grayish color and is frequently more or less eroded. 

 Operculum large with a lateral nucleus; the length of the shell some- 

 times reaching 3^ inches. 



The word "caracoles" seems to be applied by the fishermen to any 

 species of Thais or Solenosteira, and the general remarks as to edibil- 

 ity, etc., are probably referable to all the Peruvian species of these 

 groups. 



THAIS CRASSA Blainville. 



Purpura crassa Blainville, Nouv. Ann. dn Museum, vol. 1, March, 1832, p. 241, 



pi. 12, fig. 4. 

 Purpura melones Duclos, Ann. Sci. Nat., vol. 26, May, 1832, p. 105, pi. 1, fig. 2. 

 Purpura melo Reeve, Conch. Icon., Purpura, 1846, pi. 4, fig. 17. 

 Callao, taken in fish-net near San Lorenzo Island. 



Distribution. — Panama south to Callao and the Galapagos Islands. 



Shell resembling that of the last species, but destitute of tubercles 

 and only half as large; chestnut variegated with white, especially 

 anteriorly; the pillar tinged with pink, the inner edge of the outer 

 lip frequently marginated with black. 



THAIS CALLAOENSIS Gray. 



Purpura callaomsis Gray, Spicilegia Zool., vol. 1, 1828, p. 4, pi. G, fig. 11. — 

 Reeve, Conch. Icon., Purpura, 1846, fig. 79. 

 Lobos de Afuera Island, among stones at low water. 



Distribution. — Panama and southward to Callao, Peru, and the 

 Galapagos Islands. 



