NO. 1704. A COLLECTION OF SHELLS FROM PERU— BALL. 175 



TROCHITA TROCHIFORMIS Gmelin. 



Plate 23, fig. 1. 



Patella trochiformis Gmelin, Syst. Nat., vol. 8, 1791, p. 3693. 

 Calyptraea dilatata SowERBY,'Gen. Shells, fascic. 23, 1824, fig. 9. 

 Picachos. From the beach at Pisco. 



Distribution. — From Panama southward to Chile. 



Shell conical, flattened on the slopes, with a spiral suture giving 

 the effect of a spire; the surface radiately ribbed with rounded riblets, 

 the color ^^ellowish; below rounded with a more or less spiral septum 

 of a white color; the dome of the shell brownish or whitish, the margin 

 suborbicular when not disturbed by its situs. The elevation of the 

 shell is very variable, and the diameter will average about 30 mm. 



This is a very characteristic species of the Peruvian province, but 

 of no particular economic significance. 



SINUM CONCAVUM Lamarck. 



Sigaretus concavus Lamarck, Anim. s. Vert., vol. 6, 1822, pt. 2, p. 208. — Sowerby, 

 Gen. Shells, fascic. 19, 1823, Sigaretus, fig. 1. 

 From muddy sand on the inside beach at Capon (one young specimen). Caracol 

 tapadera of the fishermen. 



Distrihitio7i. — Between the equator and lat. 25° 30' S., and at the 

 Galapagos Islands. 



Shell flattened, paucispiral, the last whorl much the largest; spi- 

 rally closely sulcate, with a wide aperture and gyrate pillar; color 

 livid flesh color to pale brownish. 



The shell in the adult is nearly covered by the fleshy parts. The 

 animal plows its way under the sand, drills holes in the shells it 

 encounters and sucks the juices of its prey. It is economically inju- 

 rious through its destruction, especially in their younger stages, of 

 edible bivalves. 



TURBO MAGNIFICUS Jonas. 



Turbo magnijicus Jonas, Zcit^chr. fur Malak., vol. 1, 1844, p. 167. — Philippi, 

 Abb. u. Beschr. neue Conch., vol. 2, 1847, p. 25, pi. 6, fig. 1. 

 Dead shells and an operculum on the beach at Lobos de Afuera Island. 



Distribution. — From Manta, Ecuador, south to Callao, Perii, and 

 the Lobos Islands. 



Shell turbinate, ovate conic, turgid, imperforate, spotted or mar- 

 bled with violet and white on an olivaceous or dark-greenish ground; 

 whorls rounded, delicately axially striated; obscurely angulated 

 above, on the spire; suture distinct, not channeled; aperture large, 

 circular, internally pearly with an opaque margin; columella simple, 

 callous above; operculum nearly smooth externally. A rare shell, 

 probably without economic importance. 



