294 Transactions. 



sisting of one and a half convex whorls. Whorls 3|, flattened, 

 regularly increasing, with the sides almost straight, subquadrate 

 in section, the base somewhat excavated. Suture slightly 

 channelled. Aperture subquadrate. Outer lip sharp, with two 

 angles above and one below. Columella short, concave. Um- 

 bilicus large, scalar, with the sides inclined. Operculum un- 

 known. Diameter : maximum, 3 mm. ; minimum, 2*5 mm. 

 Altitude, 1 mm. 



Type in the Colonial Museum, Wellington. 



Obs. One dead shell only. This very interesting addition 

 to our fauna is almost identical with Discohelix retifera, Dall., 

 from the Pliocene of Florida. The operculum of our species 

 being unknown, we place it for the present in the genus Oma- 

 laxis, Deshayes. A similar form, 0. meridionalis, dredged in 

 Port Stephens, but not so elaborately sculptured, has been 

 described and figured by Mr. C. Hedley in Memoirs Austral. 

 Museum, iv, part 6, 1903, p. 351. 



41. Aclis semireticulata, n. sp. Plate XXIV, figs. 33, 34. 



Shell small, subulate with a rounded base, subrimate, longi- 

 tudinally costate and with a spiral thread on the last whorl. 

 Sculpture longitudinal and spiral ; the latter consists of some 

 minute stria? upon the base, occasionally extending above the 

 periphery, and usually absent upon the spire. The longitudinals 

 form small rounded costations, obsolete or absent upon the base, 

 and generally very variable, some fairly uniform throughout, 

 others feeble on the last whorl, and others again more or less 

 obsolete on all whorls. Colour light-horny, hyaline. Epidermis 

 very thin, glossy, membranaceous, present on a few specimens 

 only. Spire conical, longer than the body-whorl, with a blunt 

 apex. Protoconch formed by about two smooth rounded and 

 vitreous volutions. Whorls 6, regularly increasing, rounded, 

 and with a convex slightly produced base. Suture deep, mar- 

 gined above by a minute threadlet which strengthens upon the 

 later whorls, and continuing forms a distinct thread below 

 the periphery upon the body-whorl. Aperture broadly ovate. 

 Outer lip regularly rounded, slightly varicose, the varix usually 

 set a little back from the edge. Inner lip forming a small re- 

 flected callus upon the body, extending to the outer margin, 

 and upon the excavated columella, which is mostly a little pro- 

 duced below, forming an angulation of the aperture. Umbilical 

 chink very narrow or obsolete. Altitude, 3*3 mm. ; diameter, 

 1*7 mm. 



Type in the Colonial Museum, Wellington. 



Obs. A number of specimens, none with the animal. This 



