8 AMPHINEURA. [Polyplacophora, 



Sect. 1. ISCHNOCHITON, S.S. 



Valves and insertion plates thin and smooth, 1 side slit in each 

 median valve ; the scales of the girdle flat and striated, sometimes 

 smooth. 



KEY TO SPECIES. 

 A. Scales striated. 



a. Scales faintly striated, mingled with smooth scales . . longicymba. 



aa. Scales deeply grooved. 



b. Lateral areas with radial wrinkles, cut up into granules contractus. 

 bb. Lateral areas with broad concentric ridges, radiate rib- 

 lets present or indistinct. 



c. Shell with the margins subparallel, divergence 100 fulvus. 

 cc. Shell oval, larger, divergence 110-120 .. .. Parkeri. 



AA. Scales smooth, shell small . . . . . . . . luteoroseus. 



1. Ischnochiton contractus, Reeve, 1847. Plate 2, fig. 3. 



Chiton contractus. Reeve, Conch. Icon., Chiton, pi. 15, f. 78. Ischnochiton 

 contractus, Man. Conch. (1), xiv, 93, pi. 23, f. 81, 82 ; Suter, P. Mai. S.. 

 vii, 293. Chiton decussatus. Reeve, Conch. Icon., pi. 18, f. 107. C. castus. 

 Reeve, Conch. Icon., pi. 22, f. 145. Lepidopleurus speciosus, Ad. & Aug.. 

 P.Z.S., 1864, p. *92 ; 1865, p. 187. 



Shell oval, subelevated, ashy, irregularly streaked with brown- 

 olive. Anterior valve with close radiating wrinkles, broken into granules 

 by concentric grooves. Intermediate valves broadly rounded, the central 

 areas finely zigzaggedly wrinkled, this sculpture being somewhat 

 effaced on the jugum ; lateral areas with radiating, slightly divaricating 

 wrinkles, which also are sometimes cut up into granules by concentric- 

 sculpture. Posterior valve with the same sculpture as the head valve, 

 mucro median, posterior slope straight. Girdle with small, imbricating, 

 and deeply striated scales. Colour yellowish-white or ashy, sometimes 

 with longitudinal rows of brown spots in the centre or laterally ; girdle 

 light brown. Interior white, anterior valve with 14 sharp teeth, 

 intermediate valves with 1 slit on each side, posterior valve with 

 13 slits ; sinus wide, smooth ; the sutural lamina? narrow, not high, 

 rounded. 



Length, 37 mm. ; breadth, 17-5 mm. Divergence, 110. 



Type, from Tasmania, in the British Museum. 



Hob. Auckland Islands (Captain Bollons). Tasmania, Australia, 



Remarks. This species is, as far as I know, not in any New Zealand 

 collection of our shells, and in 1897 I placed it amongst the species 

 doubtfully occurring in New Zealand waters. In 1906, however, 

 Captain Bollons brought me a small specimen (9 mm. long) which 

 he had found at the Auckland Islands, and this proved to be the above 

 species. The colour is yellowish-white, with 3 longitudinal rows of 

 brown spots. The sculpture consists of the characteristic zigzag 

 wrinkles, which are very delicate, as is to be expected in such a young 

 specimen. 



