![Thumbnail: [Volume 37, 1904 page 253]](/journals/rsnz/images/rsnz_37/thumbnails/rsnz_37_00_0279_0253_ac_02.gif)
Isidora lirata, Tenison-Woods (1879).
P.L.S. N.S.W., vol. iii., 1879, p. 138, pl. xiii., fig. 6.
(1.) Lake Rotoiti (Stat. 12—From weeds in 6 ft.).—Six specimens, one only adult. The colour is light-horny, some specimens having a dark coating; the whorls are rounded, but slightly flattened below the suture, the spiral striæ are present but not very distinct. Aperture produced at the base, columella twisted. They are slightly more ventricose than the type. Shell: length, 12 mm.; breadth, 7 mm. Aperture: height, 8½ mm.; breadth, 4 mm. Shell: length, 10 mm.; breadth, 6 mm. Aperture: height, 7 mm.; breadth, 3½ mm. Shell: length, 8½ mm.; breadth, 5½ mm. Aperture: height, 5 mm.; breadth, 3 mm. Ratios: i. = 1: 1.7; ii. = 1: 2.1; iii. = 1: 1.4. i. = 1: 1.7; ii. = 1: 2; iii. = 1: 1.4. i. = 1: 1.5; ii. = 1: 1.7; iii. = 1: 1.7.
(2.) Lake Taupo (Stat. 7—Dredged with weeds in 75 ft.).—One specimen of cream colour, fragile; four whorls, shouldered down to the middle of the last whorl, carina with short bristles; shell indistinctly spirally striated; columella twisted, aperture much produced anteriorly. More ventricose than the type. Shell: length, 8 mm.; breadth, 5 mm. Aperture: height, 6 mm.; breadth, 3 mm. Ratios: i. = 1: 1.6; ii. = 1: 2; iii. = 1: 1.3.
(3.) Lake Taupo (Stat. 38—With weeds, from 80 ft.).—Many, mostly young specimens. They are of a dirty-white colour with a thin whitish coating. Whorls 4, rounded, sometimes flattened below the suture, beautifully regularly spirally striate. Columella twisted, aperture produced anteriorly. These I consider to be typical forms. Shell: length, 9½ mm.; breadth, 6 mm. Aperture: height, 7 mm.; breadth, 3 mm. Shell: length, 8½ mm.; breadth, 4¾ mm. Aperture: height, 6 mm.; breadth, 3 mm. Shell: length, 7½ mm.; breadth, 4½ mm. Aperture: height, 5 mm.; breadth, 2½ mm. Ratios: i. = 1: 1.6; ii. = 1: 2.3; iii. = 1: 1.4. i. = 1: 1.8; ii. = 1: 2; iii. = 1: 1.4. i. = 1: 1.7; ii. = 1: 2; iii. = 1: 1.6. Fig. 16 shows some teeth of the radula. A remarkable feature are the additional denticles on the outer upper side of the marginal teeth.
(4.) Lake Taupo (Stat. 38F—With weeds, from 80 ft.).—Many, mostly young shells. Very much like the specimens from
Fig. 16
![Thumbnail: [Volume 37, 1904 page 254]](/journals/rsnz/images/rsnz_37/thumbnails/rsnz_37_00_0280_0254_ac_02.gif)
Stat. 38, but the spiral striation is not so distinct, and the coating is thicker, of a greenish hue.
(5.) Lake Waikaremoana (Stat. 4—Dredging in 50 ft.).—Two “dead shells,” one adult with the apex broken off. They are rather large, of cream colour, with four rounded but slightly shouldered whorls; distinctly spirally lirate. Columella twisted, and aperture produced at base. Typical forms, though one much larger. Shell: length, 15½ mm.; breadth, 9 mm. Aperture: height, 10 mm.; breadth, 5 mm. Shell: length, 10½ mm.; breadth, 6 mm. Aperture: height, 7 mm.; breadth, 3 mm. Ratios: i. = 1: 1.7; ii. = 1: 2; iii. = 1: 1.6. i. = 1: 1.8; ii. = 1: 2.3; iii. = 1: 1.5.
(6.) Lake Waikaremoana (Stat. 5—Dredging in 50 ft.).—Six specimens, two of them quite young. The colour is light-horny, some shells with a ferrugineous coating. The whorls in some are rounded, in others shouldered and the keel ornamented with short bristles. In young specimens the spiral striation is quite distinct. Columella twisted, and aperture produced anteriorly. These again are typical forms. Dimensions of largest specimen: Shell: length, 13 mm.; breadth, 6¾ mm. Aperture: height, 8 mm.; breadth, 4 mm. Ratios: i. = 1: 1.9; ii. = 1: 2; iii. = 1: 1.6.
(7.) Lake Waikaremoana (Stat. 32—Dredging in 10 ft. to 20 ft.).—Four nearly adult and four young specimens. They are dirty-white, the longer examples with a light-brown coating. The four whorls are convex, very little flattened below the suture; spiral striation indistinct. These shells are very nearly typical. Dimensions of largest specimen:—Shell: length, 12 mm.; breadth, 6½ mm. Aperture: height, 8.5 mm.; breadth, 4 mm. Ratios: i. = 1: 1.8; ii. = 1: 2.1; iii. = 1: 1.4.