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PHYLLIDIANA. MOLLUSCA. CHITON. 147 



This species, so accurately described by Mr. Say from a single 

 specimen sent him by Dr. Ravenel of Charleston, South Carolina, 

 cannot be confounded with any other. The beautiful and conspicu- 

 ous bead-like series of dots are not found on any other described 

 species, though they partially and inconspicuously appear on C. cine- 

 reus. On account of their arrangement, I had formerly indicated the 

 shell under the name of C. pectindtus. The recent publication of 

 Mr. Say's Manuscript has established his name. The lines of dots 

 are not all of equal length, and sometimes they become so blended as 

 to form merely an elevated line, but they are generally very definite. 

 I have seen some British shells labelled C. ruler, which have precisely 

 the same sculpture ; but they are much more elegant in marking, and 

 are of a bright reddish-brown or rose-color. They cannot be C. ruler, 

 however, according to any description I have seen under that name. 



CHITON MARGINA'TUS. 



Shell ovate, the valves carinated across the middle, and pointed 

 behind ; of a dead cinereous or greenish-color, and minutely sha- 

 greened ; margin pulverulent. 



FIGURE 22. 

 State Coll., No. 167. Soc. Cab., No. 2353. 



Chiton marginatus, PENNANT ; Brit. ZooL, iv. 71, t. 36, f. 2. LIN. ; GMELIW ; 



Syst., 3206, No. 26. MONTAGU ; Test. Brit., 1. PDLTENEY ; Dorset Catal, 25, 



pi. 1, f. 2. MATON and RACKETT ; Lin. Trans., viii. 21, pi. 1, f. 2. WOOD ; 



Gen. Conch., 21, pi. 3, f. 4. SCHROET. ; Einl. in Conch., iii. 508. D'ARGEMY. ; 



Conchyl., t. 25, f. M. LAM.; An. sans Vert., vii. 492. SOWERBY ; Conch. 



Illust., f. 106 to 112. FLEMING ; Edin. Encyc., vi. 102. Brit. Anim., 289. 

 Chiton cinereus, LOWE ; Zool. Journ., ii. 99, pi. 5, f. 5. 



Shell small, ovate, moderately convex, with an elevated ridge 

 along the centre, where each of the valves projects backwards in 

 a minute beak, ending at the centre of the posterior valve ; 

 valves faintly divided into triangles ; surface otherwise apparently 

 smooth, but under the magnifier it is found to be beautifully sha- 

 greened, the granules being arranged in diamonds on every part. 

 Color a dead, dull ashen or greenish color, sometimes mottled. 

 Margin narrow, membranous, coated with a dusty pigment, which 



alternately hoary and brownish. Length J inch, breadth T 3 ^ 

 inch. 



