No. 1704. A COLLECTION OF SHELLS FROM PERU—DALL. 171 
or angulate keels; the whole shell spirally threaded, with an axially 
lamellose band appressed at the suture; shell white with an oliva- 
ceous periostracum, the threads sometimes brownish, and the interior 
of the aperture sometimes spirally brown threaded; pillar without 
plaits, the operculum with a lateral nucleus. Length about 36 mm. 
Specimens prepared for market by breaking off the greater part 
of the last whorl were also sent in’ by Mr. Coker. This species has 
been widely confused with Cymia (or Cuma) and Solenosteira. From 
the first it may be known by the absence of the strong plait or keel 
in the middle of the pillar, and from the second by its laterally 
nucleated operculum and the lamellose sutural band. 
Several other species of Thais have been used since prehistoric 
times by the natives of Central America as a source of purple dye. 
The most commonly used species there is Thais (Patellipurpura) 
patula Linneus. Many years ago the writer, at San Juan del Sur, 
Nicaragua, stained a handkerchief with the unmixed purple from 
one of these shells. Perhaps because lemon juice or other mordant 
was lacking the color faded considerably during three years that the 
handkerchief was kept, and the color was not at any time brilliant, 
resembling the water color known as “neutral tint.’’ Sefiora Zelia 
Nuttall, of Mexico City, well known for her profound ethnological 
researches, has recently read a paper before the American Association 
for the Advancement of Science on the prehistoric use of these 
Molluscan purples in Mexico and Central America. 
BURSA VENTRICOSA Broderip. 
Ranella ventricssa Broperir, Proc. Zool. Soc. of London for 1832, p. 178.— 
Sowersy, Conch. Ill., Ranella, 1839, pl. 92, fig. 116. 
Ranella tenuis Potrez and MicHaup, Galerie de Douai, Moll., vol. 1, 1837, 
p. 426, pl. 34, figs. 1, 2. 
Dredged in Callao Bay, in about 24 fathoms, near the northeast side of San Lorenzo 
Island. Also sold in Callao market, among other gastropods, under the name of 
Caracoles. 
Distribution.—Nicaraguan coast and south to Callao, Peru. 
Shell thin, whitish, obscurely rugosely sculptured or smooth, with 
lateral varices, a large aperture, with thickened and varicose outer 
lip, with a wide and deep canal near the junction of the lip and the 
body whorl. 
CYMATIUM VESTITUM Hinds. 
Triton vestitus Hinds, Zool. Sulphur’s Voy., Moll., p. 11, pl. 4, fig. 1, 1844. 
Chincha Islands, among the rocks. 
Distribution.—West coast of Central America and southward to 
the Chincha Islands, Peru. ; 
Shell rather large, thin, with a moderately elevated spire and 
strong spiral ribs; surface covered with a dense lamellose periostracum 
