CHITON. 165 



The lateral areas are separated from the central areas by an 

 oblique curved ridge, but scarcely raised ; sculptured with 6 or 7 

 low radiating riblets, somewhat decussated by longitudinal sub- 

 obsolete riblets. The central areas are sculptured with longitudinal 

 riblets finer than those of the lateral areas. End valves having 

 radiating riblets and less distinct concentric lirse, the umbo of pos- 

 terior valve near the front margin. 



Interior pale blue ; sinus flat, toothed; anterior valve having 10, 

 central valves 1, posterior valve 13 slits; teeth blunt, pectinated. 



Girdle clothed with smooth, convex, imbricating scales. 



Length 53, breadth 34 mill. 



Length 56, breadth 31 mill. 



Valparaiso, Chili. 



C. cumingsii FREMBLY, Zool. Journ. iii, p. 198, suppl. pi. 16, f. 

 3. C. cumingsi DH. in Lmk., An. s. Vert, vii, p. 500. C. cumingii, 

 SOWB., Conchol. Illust., f. 32. REEVE, Conch. Icon., t. 1, f. 2. 



This well-known species is of a bronze-olive color, closely lineated 

 with brown or olive. The lines are not distinctly enough shown in 

 the figures. The range of variation in contour and color-pattern is 

 considerable. It has been reported from the Cape Verde Is. (Nouv. 

 Arch, du Mus. 1881, p. 282), but there cannot be much doubt that 

 the citation is based on a false locality label. 



C. STOKESII Broderip. PI. 30, figs. 25, 26 ; pi. 32, figs. 50-53. 



Shell oval, moderately elevated or depressed, the back carinated, 

 side-slopes straight. Brownish-black, toward the middle often 

 more or less marbled longitudinally with dirty white. 



Lateral areas somewhat raised, closely sculptured with radiating, 

 irregularly granulous and anastomosing riblets. Central areas 

 sculptured throughout with low close longitudinal riblets, often made 

 slightly granose by the lines of growth. End valves covered with a 

 net- work of nodose riblets generally very much interrupted ; umbo 

 of posterior valve near the front margin. 



Inside smooth, varying from blue-white to light blue, the sutural 

 plates paler, all of the valves marked with a spot of dull brown. 

 Sinus deep, rather narrow and angular, jaggedly toothed. Anterior 

 valve having 16, central valves 1, posterior valve 15-16 slits. 



