in C. IIKDI.KV AND A. F. IIXSSKT HULL. "J 7 7 



6. Chiton corypheus, ii.sp. 

 (Plate xii., figs.6, 6a, 6b, 6r.) 



Shell elevated, carinated, side slDpes convex, of medium size. 

 Colour extremely variable, both in shade and pattern, yet two 

 groups appear, one lighter and the other darker. The girdle is 

 usually tesselatefl with light and dark. A line along the dorsal 

 area is apt to be differentiated l)y being lighter or darker than 

 the rest. Frequently the umbones are tipped with pink. Some- 

 times one or two valves oppose a sharp contrast to the rest. 

 No monochromes appear; buff", olive-green, pink, and rarely w hite 

 display an infinite variety of splashes or marbling. 



Anterior valve with 14-18 strongly raisefl granular riblets, 

 increasing in size towards the margin; in mature examples the 

 riblets are multiplied l)y splitting of the fewer radii of the 

 yo^^nger shell. 



Posterior valve : mucro prominent, in front of the centre, with 

 14-16 radial riblets similar to anterior valve; central area similar 

 to median valves. 



Median valves : lateral areas raised, with 2-4 prominent 

 granular riblets with shorter ones intercalating with age; central 

 areas furrowed by 8-10 longitudinal sulci becoming obsolete 

 anteriorly; jugal tract smooth and polished. 



Girdle unusually l)road, scales finely transversely striate, 

 polished at the margin. 



Interior, green becoming paler at the margin. Sinus narrow 

 and deep. Anterior valve having 8, median 1-1, and posterior 

 valve 10 slits. 



Length 18 mm., breadth 10 mm. 



Station. — On the under surface of loose stones in pools on the 

 coi-al reef; on the under side of or in the interstices between large 

 basalt boulders, or on the surface of the rock in "pot-holes." 



Habitat. — Noi-folk Island. 



Remarks. — This handsome shell is \ery plentiful at all points 

 on the coast. On the coral reef at Emily Bay and amongst the 

 sheltered rock pools at Bumboras Bay, immature examples are 

 common, and show a wonderful variation in brilliancy of colour- 



