l62 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



where it is replaced on the base and canal by the usual coarser stria- 

 tion. The variety crctacea Reeve (as Buccinum), is distinguished 

 by the absence of the fine striation on the greater part of the shell, 

 more regular and stronger ribs, and more expanded aperture. It was 

 dredged at stations 4779, 4994, 4795. and 5005, in 47 to 190 fathoms. 

 The young are sometimes purplish brown, with the axial ribs ivory- 

 white, stopping short at the edge of the base, which is sharply spi- 

 rally grooved, making a very striking-looking shell. The adults 

 usually have the spire much eroded, with about 13 ribs on the penulti- 

 mate and 15 to 18 on the last whorl, obliquely arcuate, with the con- 

 cavity on the anterior side. 



Genus MOHNIA Friele 

 MOHNIA MICRA Dall, n. sp. 



Shell quite small, acute, slender, greenish olive over a chalky sub- 

 stratum, more or less eroded ; whorls five or more, the nucleus eroded, 

 the suture minutely channeled ; whorls smooth except for incremental 

 lines, moderately rounded ; aperture white, outer lip thin, slightly 

 arcuate ; body with a wash of callus ; pillar white, twisted, almost 

 pervious ; canal moderately produced, twisted, almost pervious ; on 

 the back of the canal and base there are a few faint spiral striae. 

 Lon. of shell, 15; of last whorl, 10.5; of aperture, 7; max. lat. of 

 shell, 7 mm. 



Station 4813, in 200 fathoms, off Sado Island, Japan Sea, July 

 18, 1906. U. S. Nat. Mus., 110,499. 



This is the smallest species yet described. 



MOHNIA SORDIDA Dall, n. sp. 



Shell small, slender, acute, with a strong blackish or brownish 

 periostracum, paler or even greenish white on the base and pillar, 

 with a narrowly channeled suture and about six whorls ; nucleus 

 eroded, shell more or less coated with a rusty, earthly deposit ; early 

 whorls with a few obsolete spirals, the most prominent one peripheral, 

 but absent from the last whorl, where only obsolete impressed lines 

 and microscopic spiral striation remain ; axial sculpture only of in- 

 cremental lines, concavely arcuate; aperture narrow, outer lip thin, 

 sharp ; throat brownish or white, pillar greenish white, with a wash 

 of callus, twisted, recurved, pervious ; operculum paucispiral, brown- 

 ish. Lon. of shell, 27; of last whorl, 18; of aperture, 13; max. lat. 

 of shell, 9 mm. 



Station 5032, in 300 fathoms, Tsugaru Strait, Japan, September 

 30, 1906. U. S. Xat. Mns., 110,496. 



