NO. 2207. WEST AMERICAN MELANELLID MOLLUSKS—BARTSCH. 349 



acute; inner lip strongly curved and moderately reflected; parietal 

 wall glazed by a thin callus. 



The type and 31 specimens (Cat. No. 267652, U.S.N.M.) were 

 dredged hy the U. S. Bureau of Fisheries steamer Albatross, in 3 

 fathoms, in the head of Concepcion Bay, Gulf of California. The 

 type has lost the first whorl; the 14 remaining measure — length, 

 17.5 mm.; diameter, 6.5 mm. 



The following specimens have been examined : 



NISO INTERRUPTA Sowerby. 



Plate 48, figs. 1, 3. 



Eulima interrupta Sowerby, Proc. Zool. Soc. London, 1834, p. 7 

 rupta Sowerby, Thes. Conch., 1854, p. 801, pi. 170, fig. 9. 



Niso inter- 



Shell broadly elongate-conic, deeply and widely umbihcated, 

 bluish-white, pohshed, marked with irregularly disposed varicial 

 streaks of rust brown. Early whorls weU rountled, later ones less 

 rounded and sUghtly ex curved at the appressed summit, marked by 

 numerous hues of growth and exceedingly fine microscopic spiral 

 striations. Summit of the whorls appressed, falling a little below 

 the angulated periphery of the preceding whorl, thus causing the 

 precetling whorl to appear as shghtly overhanging the suture. 

 Periphery of the last whorl angulated. Base short, well rounded, 

 marked hke the spire; umbilicus equal to about one-fifth of the greater 

 diameter of the shell. Aperture oval, drawn out into an acute 

 angle at the junction of the inner lip and basal lip; posterior angle 

 acute; outer lip thin; inner lip strongly curved and shghtly revolute; 

 parietal wall covered by a thin callus. 



Two specunens (Cat. No. 122793, U.S.N.M.) were dredged ])y the 

 United States Bureau of Fisheries steamer Albatross at station 2805 



