Chiton.] AMPHINEURA. 33 



. Central areas smooth ; no longitudinal ribs. 



b. Lateral areas with radiate granose ribs . . . . Sinclairi. 



bb. Lateral areas without radiate ribs . . . . . . Torri. . 



a. Group of Chiton pellisserpentis. 

 Central areas with rather fine longitudinal sculpture, or smooth. 



1. Chiton pellisserpentis, Quoy and Gaimard, 1835. Plate 2, fig. 12; 

 Plate 4, fig. 6. 



Chiton pellisserpentis, Q. & G., Voy. Astrol., iii, 381, pi. 74, f. 17-22 ; Man. 

 Couch. (1), xiv, 173, pi. 37, f. 14-17 ; P. Mai. S., ii, 195. C. squamosus, 

 L. : Wissel, Zool. Jahrb., xx, 619, not of Linne (anatomy). 



Shell oval, rather elevated, side slopes somewhat convex, olive or 

 brown, marked with black along the ridge. Anterior valve larger and 

 much more elevated than the posterior, with numerous regular rows 

 of distinct tubercles, the rows sometimes increased by splitting, inter- 

 spaces finely decussate. Of the intermediate valves, the first is larger 

 longitudinally than the others, central areas with strong irregular 

 growth-lines, and fine longitudinal riblets ; these are broader in front, 

 stouter near the margins, extending over the jugum on the first valve, 

 but usually leaving the ridge smooth on the following 5 valves ; lateral 

 areas moderately raised, with 3 or 4 rows of distinct tubercles of various 

 form, interstices minutely decussate. Posterior valve small, with 

 regular rows of tubercles, depressed, mucro in front of the middle, 

 low, posterior slope almost straight. Girdle moderately wide, banded 

 with darker and lighter ; scales rather large and wide, convex, often 

 subcarinated in the middle, microscopically very finely striated. 

 Colour usually dull, dingy-olive or olive-green marked with black on 

 the ridge and on the sides of the valves. Sometimes 2 or more valves 

 are light grey, the others greenish or dark brown, rarely the ground- 

 colour is orange ; one specimen I have is beautifully bluish-green 

 marked with white ; the girdle is always of the same colour as the 

 valves, but lighter. Interior blue, indistinctly blotched with olive- 

 green ; anterior valve having 12, central valves 1, posterior valve 

 12 slits ; teeth blunt, pectinated ; sinus broad and deep, smooth or 

 hardly denticulate ; sutural plates rounded ; valve-callus heavy and 

 smooth ; eaves broad. 



Length, 30 mm. ; breadth, 23 mm. Divergence, 95-120. 



Dentition. Hutton, T.N.Z.I., xv, 129, pi. 16, f. 1. 



Type, from Tasman Bay, in Mus. Hist. Nat., Paris. 



Hob. Throughout New Zealand the most abundant Chiton ; Chat- 

 ham Islands. Tasmania. 



Remarks. Its sculpture is frequently obscured or lost by erosion. 

 A specimen with 5 valves only is recorded by Iredale (T.N.Z.I., xl, 

 375, pi. 31, f. 2). 



Fossil in the Pliocene. 



2 Moll. N.Z 



