Mestayer. — New Zealand Mollusca. 179 



The true numbering is Lorica volvox, fig. 22 ; Onithochiton unchdatus, fig. 24. 

 So far as I can tell from the very poor figure, a specimen of L. haurakiensis 

 is there shown, but accurate determination is almost impossible. 



CHITONIDAE. 



Rhyssoplax Tliiele (5). 

 Rhyssoplax oliveri n. sp. (Plate XXXVJII, figs. 9-11.) 



Huetataka, Lyall Bay, Cook Strait, N.Z. 



Shell small, oval, smooth, with a subglossy surface, the side slopes 

 almost straight. Anterior valve smooth except for six tiny nodules close 

 to the girdle, and slight traces of radial riblets. The animal is dried inside, 

 but the eight slits are easily seen under a pocket-lens. Median valves 

 slightly beaked, the jugal and pleural areas smooth, lateral areas raised, 

 well defined, with very faint traces of radial sculpture. Interior one slit, 

 sinus hidden by the animal, colour bluish, insertion plates probably white. 

 Posterior valve, mucro central, moderately prominent, posterior slope rather 

 steeply concave, bounded by a nearly smooth rib. Interior eight slits. 



Colour : Ground-colour cream, mottled with dull green, and small 

 longitudinal flecks of light brown ; the whole surface densely covered with 

 microscopic white speckles. 



Girdle : Scales very finely closely striate, rounded, the largest along 

 the centre, the outer edge with three or four rows of very fine outstanding 

 spicules, which are easily rubbed off. Colour creamy transversely banded 

 with green and tinged with brown. 



Measurements : Length, 10-5 mm. ; breadth, 7 mm. 



Material: The holotype, obtained by W. R. B. Oliver, 13th January, 

 1918, and presented to the Dominion Museum. 



Remarks. — This species appears to be more closely related to Rhyssoplax 

 translucens (H. & H.), of Australia, than any other New Zealand member 

 of this genus. It differs from R. translucens in being smoother and much 

 smaller, while the girdle-scales are proportionately larger and rounder. 



SCAPHANDRIDAE. 



Damoniella Iredale (6). 

 Damoniella alpha n. sp. (Plate XXXVIII, fig. 12.) 



Shell small, narrow, ekmgately cylindrical, solid. Sculpture about thirty 

 flat spiral ribs, with very narrow grooves between them. The grooves 

 are rendered punctate by a large number of fine vertical growth-striae, 

 which do not cross the spiral ribs. Aperture the entire length of the shell, 

 narrow anteriorly, somewhat inflated posteriorly. Outer lip sharp, very 

 slightly crenulated by the spiral grooves. Vertex pierced by a very narrow 

 axial perforation. Columella short, vertical, slightly concave, very lightly 

 reflexed towards the tiny umbilical chink. 



Measurements : Length, 7 mm. ; breadth, 4 mm. 



Material : The holotype, in the Dominion Museum, collected by Dr. 

 J. A. Thomson at Blue Cliffs, Otaio River, South Canterbury, in 1917 

 (Awamoan). 



Remarks. — This specimen was placed by the late Mr. Suter in the genus 

 Roxania Leach (1847), but Iredale points out that this is invalidated by a 



