246 ONITHOCHITON. 



or olive-gray, becoming yellow toward the apices of the valves, each 

 valve elegantly painted throughout with concentric olive or brown 

 lines, and having a darker dorsal band ; or (2) olive-green at the 

 sides, with a broad light triangle on the ridge of each valve, in the 

 middle of which there is a stripe of rich chestnut or of green ; the 

 whole concentrically lineolate with irregular green and cream-white 

 lines. 



The valves are beaked ; lateral areas but little raised, and either 

 smooth or sculptured with 4 or 5 low, more or less obsolete, beaded 

 radiating riblets ; and showing under a lens, a band of eye-dots near 

 the front margin. Central areas smooth and polished. Anterior 

 valve having obsolete radiating riblets, and rays of eyes, the eye- 

 rays variable in number, width, and degree of coalescence, the 

 individual eyes being very mutable in number and position. Pos- 

 terior valve very shortly subtriangular, the distance from sinus to 

 mucro being but little more than one- third the width of the valve's 

 tegmentum. 



Interior white, marked with reddish-brown under the beak in each 

 valve. Sinus delicately toothed, deep and angular ; sutural-plates 

 higher toward the sinus jthan toward the outer edges of the valves- 

 Anterior valve having 8 slits, median valves 1 slit ; teeth obtuse, 

 closely and sharply pectinated outside and on the summits. Poste- 

 rior valve having a narrow, slightly convex ridge in place of the 

 insertion plate. 



Girdle reddish or brown. 



Length 25, breadth 16 mill. ; divergence 110. 



Length 27, breadth 14 mill.; divergence 110. 



New Zealand, at Bay of Islands (Q. & G.) ; Auckland to Dunedin 

 (Hutton) ; Chatham Is. (Hutton.) 



Chiton undulatus Q. & G., Zool. Astrolabe, p. 393, t. 75, f. 19-24. 

 KEEVE, Conch. Icon., t. 16, f. 87, 90. Onithochiton undulatus 

 ADS., Genera, i, p. 476, t. 54, f. 3. Tonicia undulata HUTTON, 

 Man. N. Z. Moll., p. 114 (1880.) 



The comparative breadth of this species is subject to considerable 

 mutation, as well as the coloring and the development of weakly 

 beaded riblets on the lateral areas. In some specimens these riblets 

 are not perceptible. Occasionally the sides of some valves are uni- 

 form greenish, lacking brown lines and angular white lines. 



This species has been reported from Tasmania, but on insufficient 

 authority. 



