294 GASTROPODA. [Pectinibrnnchia. 



Fossil. A few species are known from the Miocene, but not in New 



Zealand. 



KEY TO SPECIES. 



A. Shell rather large, auriform ; axis widely open to the apex . . cerebroides. 



B. Shell small, oval ; axis narrowly open to the apex . . . . ophione. 



1. Lamellaria cerebroides, Hutton, 1883. Plate, 44 fig. 8. 



Lamellaria cerebroides, Hutt., T.N.Z.L, xv, 1882 (1883), 122 ; M.N.Z.M., 59. 

 Marsenia cerebroides, Hutt., Index, 80. 



Shell moderately large, auriform, thin and fragile, shining, white. 

 Sculpture consisting of fine growth-striae and folds, and there is just 

 a trace of microscopic spiral striation. Colour a slightly yellowish 

 white. Epidermis thin, transparent and rather iridescent, overlapping 

 the peristome, and covering the inner lip. Spire very short, depressed. 

 Protoconch minute, of 1J oval whorls, which are smooth and flatly 

 convex. Whorls 3|, rapidly increasing, the last very large, convex, 

 flattened below the suture. Suture impressed. Aperture broadly 

 ovate. Outer lip membranaceous, broadly arched. Basal lip hori- 

 zontal. Columella broadly arcuate, with a thin and rather sharp 

 edge. Inner lip forming a narrow, wrinkled, and yellowish band. 

 Axis widely open to the apex. 



Diameter Maj., 22 mm. ; min., 15 mm. : height, 14 mm. 



Animal with the mantle smooth, but much wrinkled, resembling 

 the convolutions of the brain, the shell completely internal. Colour 

 reddish-brown, marbled with yellowish-grey ; yellow when preserved 

 in alcohol. The mantle is considerably expanded and waved laterally, 

 trilobed in front. Tentacles short, subulate, with blunt tips ; eyes 

 at their outer side, sessile. The intromittant organ is large, drawn 

 out to a fine point. 



Dentition unknown. 



Hob. Near Dunedin, type (G. M. Thomson) ; Akaroa Harbour, 

 at low-water mark (H. S.). 



2. Lamellaria ophione, Gray, 1850. Plate 46, fig. 2. 



Lamelluria ophione, Gray, P.Z.S., 1849 (1850), 169 ; A.M.N.H. (2), vii, 1851, 

 69. L. Indica, Leach : Hutton, C.M.M., 21 ; not of Leach. Coriocella 

 ophione, Gray, M.N.Z.M., 59. Marsenia ophione, Gray, Index, 80. 



Shell oblong, elongate, pellucid, thin, white. Sculpture consisting 

 of fine growth-lines and folds, crossed by faint microscopic spiral striae. 

 Colour white. Epidermis very thin, transparent, lightly iridescent, 

 and shining. Spire very small and short. Protoconch of 1^ smooth 

 flattish whorls, the nucleus oval and minute. Whorls 3, very rapidly 

 increasing, convex, the last very large. Suture impressed. Aperture 

 oblique, broadly ovate. Outer Up sharp and thin, the epidermis usually 

 overlapping. Columella concave, parietal wall convex. Inner lip 

 spread as a narrow band over columella and parietal wall. The whorls 

 are centrally loosely coiled up, leaving a narrow opening through 

 which, looking up from the base, the apex can be seen. 



