no. 1704. A COLLECTION OF SHELLS FROM PERU—DALL. IG rer 
Shell conoidal, heavy, solid, elevated, minutely 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.—Sowersy, 
Conch. Ill., 1834, fig. 11 (mot 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. Il., 1836, Fissurella, fig. 36. 
Lapa. Taken at Mollendo, July 23. These are probably utilized lke the pre- 
ceding species. 
Distribution.—From the island of Chiloé 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 projections 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.—RereEve, Conch. Icon., 
Fissurella, 1850, fig. 11. 
Lapa. One young specimen from the rocks at the north end of the Callao water 
front. 
Distribution.—Straits of Magellan and northward 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.N.M.vol.87—09——12 
