DIAGNOSIS.—This stout black species is characterized by its low, dome-shaped spire, which in larger specimens may appear moderately elevated because of the downward flexure of the last whorl at the aperture. The penultimate whorl is marked by fine irregularly and more or less distantly spaced incised lirae, which on the latter half of the body whorl may become obscure furrows.
Width 18.66 mm ; Height 18.03 mm

In most papers on the mollusks of Easter Island
N. morio and the species N. lirellata have been lumped together; e.g., the material identi¬fied as N. atrata Reeve by Dali (1908a:437) consisted of 18 specimens of N. lirellata, new species, and three of N. morio (Sowerby). Dr. Bengt Hubendick (in litt.) informs me that the material reported on by Odhner (1922:248) and listed as Nerita morio (Sowerby) contains both species. In the material collected by Father Englert, sent to me by the California Academy of Sciences, and reported on by Steele (1957: 112), both species were mixed and identified as N. morio.
Nerita morio differs most noticeably from N. lirellata in lacking the pronounced spiral grooves and ridges found on the latter, in possessing a more or less shiny surface, not dull as in N. lirellata, and in the columella lip having several weak teeth, rather than only one; the exterior of the operculum is tinged more or less extensively with orange and is not uniformly gray. There is no apparent ecological separation of the two species; on two occasions I found both species on the same rock in about equal proportions. Occasionally, however, I did find a segregation of these species. In Hanga Papara N. morio was found on rocks at the shore line down to 1 ft (0.3 m), while N. lirellata was found under rocks in 2 to 3 ft (0.6 to 0.9 m) of water. Cernohorsky (1972a:49) in his remarks under Nerita picea Recluz, 1841, mentions that N. morio has been recorded from Indonesia by Adam and Leloup (1938:55). I have been able to examine these specimens through the courtesy of Dr. W. Adam and Dr. J. Van Goethem and find that they are not N. morio but belong to an as yet undetermined species. I have at the same time studied material of what was identified as N. picea from Indonesia by Adam and Leloup (1938:55) and find that they are N. ocellata Le Guillou, 1841; Nerita picea is restricted to the Hawaiian Islands. Nerita carbonaria Philippi, 1844, which Cernohorsky (1972a: 49) puts in the synonymy of N. morio, is a nomen dubium and must remain as such for the present until Philippi’s type can be located.

Eastern Islands. Chile.

RANGE.—From Easter Island and Sala y Gomez westward in a narrow band through the Pitcairn Islands and Rapa to the Gambier and Austral Islands (Figure 6). Recluz gives the Marquesas Islands as the type-locality of Nerita haneti, but extensive collecting on Nuku Hiva and other Islands in the group has not turned up this species.
HABITAT.—On and under rocks in tide pools, and on rocks at water's edge and in wave-surge area.