CHITON, 



This -pi-firs is amply dislin.Lrni.-hed from 1'. /nrlf/'ifn.-- hv tin- wider 

 sinus, dillrtvnt Ooloriagj and l>y tlir iniirli more porous lines |f 

 iiiLT toward llir .-Ills, and (lir eon>piriiou>ly pomii- triaiiL'l' under tin- 

 dorsal ridi:r of each valve, as shown in li: 



Species of the West coast of the Americas. 



This is a natural jrroup of lar.L r e species, character i/fd bv the 

 generally somber color, large smooth scales, and anterior nuiero. 

 l!<td.*!'t is a tangent from this circle of speei 



C. LJEVIGATUS Sowerby. PL 34, figs. 68, 69, 70, 71. 



Shell oval, subdepressed or elevated, carinated, the side-slopes 

 somewhat convex. Surface smooth. Colors soft and blended, 

 ing from purple-gray to olive, lighter in the middle, where there are 

 three irregular longitudinal series of black or dark blotches ; back 

 edge of each valve often articulated with light and dark spots. 



The lateral areas are a little raised ; whole surface polished, show- 

 ing a microscopic quincuucial granulation under the lens. Mucro 

 unusually close to the front edge of the tail valve, almost marginal. 



Interior dark green-blue ; the sutural plates lighter but having a 

 large dark green or blackish blotch at the base of each. Sinus deep, 

 si jiiare, with a convex row of jagged teeth. Anterior valve having 17, 

 central valves 1, posterior valve 21 narrow slits; teeth blunt, deeply 

 laciniate ; eaves short, narrow, spongy. 



Girdle wide, tessellated with alternate light and dark. 



Length 55, breadth 38 mill. 



Length 85, breadth 55 mill. 



Gulf of California to Afif 



Chiton lavigatus Sown., P. Z. S. 1832, p. ~M ; Conch. Illustr., f. 

 18*. REEVE, Conch. Icon., t. 7, f. 35. Chiton artictthttiis Sowi:i:i:y. 

 P. Z. S. 1832, p. 59; Conch. Illustr., f. 18. Ki i h. Icon., 



t. 2, f. 7. 



Sowerby's description of Icevigatus precedes that of //7/V;/A////x in 

 the P. Z. S., and since the two forms prove to belong to one 

 species, the former name must be accepted. Fig. 69 represents the 



There is considerable variation in the decree of elevation and in 

 the contour, but the extremes seem to be connected most intimately 

 by specimens intermediate in form. This species has a general 



