30 AMPHINEURA. [Polyplacopliora. 



jugum ; the valves are subcarinate and beaked. Posterior valve small, 

 the mucro central, with a smooth triangular area in front, beyond 

 which the whole surface is granular, the granules being comparatively 

 large. Girdle thick, fleshy, beset with microscopic white spicules : 

 there are sutural tufts of white spicules, 7 on each side, and 4 in front 

 of the head valve. Colour very variable, adult specimens showing 

 mostly a pinkish colour, yellowish on the back, but young shells have 

 sometimes a most beautiful colour-arrangement, the granules being 

 white, pink, light brown, and light blue. The jugum is mostly reddish- 

 brown with triangular spots. The girdle is light fulvous with small 

 patches and radiate bands of whitish-yellow. Interior white, but 

 the centre of the valves except the head valve is pink ; anterior valve 

 with 5 slits, intermediate valves with 1 slit on each side, teeth strong ; 

 posterior valve with a low thick insertion plate and 4 short slits ; sinus 

 rather narrow and deep ; sutural lamina? short and wide, rounded ; 

 valve-callus stout. 



Length, 17 mm. ; breadth, 13 mm. Divergence, 100-105. 



Type in the Dominion Museum, Wellington. No locality men- 

 tioned. 



Hob. Cook Strait ; Foveaux Strait, in 15 fathoms ; Hauraki 

 Gulf, in 25 fathoms ; Auckland Islands (Captain Bollons) ; Bluff : 

 Queen Charlotte Sound, in 6 fathoms (Captain Bollons). 



5. Acanthochites violaceus, Quoy and Gaimard, 1835. Plate 2, 

 fig. 11 ; Plate 4, fig. 5. 



Chiton violaceus, Q. & G., Voy. Astrol., iii, 403, pi. 73. f. 15-20. Acan- 

 thochites violaceus. Q. & G., Man. Conch. (1), xv, 39, pi. 3, f. 67-73 ; P. 

 Mai. S., ii, 193. Chiton porphyreticus, Reeve, Conch. Icon., pi. 10, f. 56. 

 Acanthochites violaceus, Q. & G. : Plate, Zool. Jahrb., v, 315: Wissel. 

 op. tit., xx, 616, pi. 21, f. 30 ; pi. 23, f. 31, 32 (anatomy). 



Shell elongated, rather depressed ; the valves all of the same width, 

 except the last, which is narrower ; colour purple-brown ; girdle 

 very wide, but narrower behind. Anterior valve having 5 pro- 

 minently projecting lobes, corresponding to radiating rounded ribs, 

 the scale granules of the surface coalescing more or less on these ribs. 

 Intermediate valves having the tegmentum trilobate, much narrowed 

 in front, convex, polished, sculptured with elongated punctures along 

 the sides ; latero-pleural areas sculptured with pebble-like low granules, 

 coarser and often confluent along a diagonal line from the beak to the 

 outer anterior angle. Posterior valve having the tegmentum slightly 

 broader than long, the mucro low, slightly post-median. Girdle wide, 

 leathery, smooth except for a minute pore at each suture and 4 around 

 the head valve, each pore bearing a small tuft of white spicules, usually 

 broken short. Colour typically a rich dark purple-brown, the girdle 

 darker, varying to violet, with a buff triangle at the ridge of each 



