64 Macrteay Memoriat Vouume. 
with 5 or 6 spiral ribs and a smooth base. Suture well marked. Aperture 
ovate, flattened anteriorly, and the outer lip rather straight. Length 5 mm. 
Locahity.—Wanganui, Petane. 
Genus RISSOA. 
Key to the species. 
1. Spire whorls longitudinally ribbed. 
Body whorl smooth Ss or sae .. KR. rugulosa. 
a ,, With one spiral groove bot ove. Ate 2ULDKESSA, 
* ,, With several spiral grooves. 
Whorls 5 cas ae a ane soot ta SVaRGIe. 
i. 6 or 7 aa Eee R. rugosa. 
2. Spire whorls not longitudinally ribbed. 
Whorls smooth, not polished... ape ... RR. annulata. 
, finely spirally striated... ce R. emarginata. 
Body whorl] spirally grooved, spire whorls smooth 2. sewzesulcata. 
Rissoa rucuLtosa, Hutton, Cat. Marine Moll. of N.Z. p. 28. 
| (Plate vit. fig. 63.) 
Whorls 7, smooth, obscurely longitudinally ribbed, aperture ovate, pointed 
behind, peritreme continuous. Length 8 mm. 
Locahity.— Petane. 
Rissoa impressa, Hutton, Trans. N.Z. Inst. Vol. XVII. p. 321. 
(Plate vin. fig. 64.) 
Shell pupiform. Whorls 5, the two first smooth, the others longitudinally 
plicated ; base of the body whorl smooth ; a single spiral groove just below the 
suture, which is margined. Aperture broadly ovate ; peritreme continuous and 
rather patulous. Length 2mm. 
Locality.— Petane. 
Rissoa Grapata, Hutton, Trans. N.Z. Inst. Vol. XVII. p. 321. 
(Plate vu. fig. 65.) 
Shell small, ovate, cancellated. Whorls 5, gradated; the two first smooth 
and polished ; the others longitudinally and spirally ribbed. Longitudinals about 
