54 THE NAUTILUS. 



Aperture oblique, circular, the peristome blunt, continuous, strength- 

 ened by a very sti'ong external rib which is beveled to the lip-edge. 

 Operculum yellow, thin. Alt. 2.7; diam. 3.6 to 4 mm. Tanega- 

 shima, Osumi. (Mr. Hirase, no. 916.) 



Readily dis^tinguished by the excessively heavy collar behind the 

 lip and'the comparatively conspicuous spiral threads. ( Vmctus, bound, 

 in allusion to the heavy, hoop-like lip-rib.) 



3Iacroc]i[amys semisericata n. sp. Shell perforate, moderately 

 depressed, dark reddish-brown, thin and somewhat translucent; the 

 surface polished below, dull with a silken sheen at the periphery and 

 above. Sculpture of excessively fine, close, slightly waved, parallel, 

 slightly oblique rib-strise above, extending from the apex to below 

 the periphery, the base smooth. Whorls 4^, slowly increasing, 

 convex, separated by an impressed suture, the last much wider, 

 rounded at the peripliery. Aperture oblique, lunate ; peristome 

 thin and simple, dilated at the columellar insertion. Alt. 3, diam. 

 5.2 mm. 



Kurozu, Kii, Types no. 83374, A. N. S. P., from no. 935a of Mr. 

 Hirase's collection. Slightly smaller specimens were found at 

 Nachi, Kii, Mr. Hirase's no. 955. 



Distinguished from M. cerasina v, awaensis and 31. tanegasMmce 

 by the silken lustre of the upper surface, produced by fine parallel 

 strife. It is much smaller than aivaevsis. {Semisericatits^ clothed half 

 in silk.) 



Zonitoides subarboreus n. sp. 



Shell extremely similar to Z. arborevs (Say), from which it 

 differs in the wider, less deeply lunate aperture, and the slightly 

 wider umbilicus. The shell is brownish yellow. Surface glossy, 

 irregularly striate, smoother below, without spiral stria?. Whorls 

 A\, convex, separated by an impressed suture. Alt. 2.7, diam. 

 6 mm., or slightly smaller. 



Hachijo-jima, Izu. Types no. 83375, A. N. S, P., from no. 951 

 of Mr. Hirase's collection ; collected by Mr. Nakada, 1902. 



This species is more depressed than Z. nitidiis, and the base is 

 less convex. Tf found in the United States, the differences from Z. 

 arboreus would hardly be noticed ; but its location on an island over 

 one hundred miles off middle Japan, together with the slight diver- 

 gence noted above, seem to indicate a distinct species. {Subarboreus 



