» 



NO. 1704. A COLLECTION OF SHELLS FROM PERU—DALL. 177 



Shell conoidal, heavy, solid, elevated, niinutely perforate, black 

 or purplish; whorls five or six, slightly convex, smooth; last whorl 

 rounded at the periphery; base flattish, deeply eroded in front of 

 the aperture; outer lip thick, lirate within, aperture small, oblique; 

 umbilicus circular, minute; the pillar small, oblique, distinctly tri- 

 dentate at the anterior end; diameter about 16 mm. 



FISSURELLA CRASSA Lamarck. 



Plate 24, figs. .5, 6. 



Fissurella crassa Lamarck, Anim. s. Vert., vol. 6, 1822, pt. 2, p. 11. — Sowerby, 



Conch. 111., 1834, fig. 11 (not fig. 2, nor F. crassa Sowerby, Gen. Shells, 



1828). 



Lapa. Sometimes called "pata de burro," though this name is more generally 



applied to another form. Taken on rocky shores of the Pescadores Islands near 



Ancon; also at the Chincha Islands in similar places abundantly; also at Mollendo. 



Used for food and bait. 



Distribution. — Coast of Chile and Peru, and the Galapagos Islands, 

 and southward to the Straits of Magellan. 



Shell oblong, depressed, with a subcentral foramen, sculptured only 

 with faint concentric and radiate undulations, especially in front; 

 color brownish; inside within the muscular scar pinkish, outside of 

 it yellowish white with a narrow brown margin. Length about 85 

 mm. 



FISSURELLA COSTATA Lesson. 



Fissurella costata Lesson, Voy. Coq., vol. 2, 1830, p. 410. 

 Fissurella chilensis Sowerby, Conch. 111., 1836, Fissurella, fig. 36. 

 Lapa. Taken at Mollendo, July 23. These are probably utilized like the pre- 

 ceding species. 



Distribution. — From the island of Chiloe northward to Mollendo, 

 Peru. 



Shell rounded oval, depressed, with the apex a little in front of 

 the center; with radiating riblets. Perforation small, contracted in 

 the middle by two small i^rojections from each side; color grayish, 

 rayed with brownish olive. Length about 40 mm. 



FISSURELLA NIGRA Lesson. 



Fissurella nigra Lesson, Voy. Coq., vol. 2, 1830, p. 412. — Reeve, Conch. Icon., 

 Fissurella, 18.50, fig. 11. 

 Lapa. One young specimen from the rocks at the north end of the Callao water 

 front. 



Distribution. — Straits of Magellan anil northwartl to Peru and the 

 Galapagos Islands. 



Shell large, oval, conical, the summit in front of the middle; color 

 black or purplish black, not rayed; surface, except for faint radial 

 striation, smooth; foramen oblong, in young specimens tridentate; 

 inside the shell is white with a black margin. Length up to 100 mm. 



Proc,X.M,vol.37— <)9 12 



L 



