POLYPLACOPHORA. 115 



areas covered with slight radiating ridges, which branch off toward 

 the edges. The colors are sufficiently variable to justify the name 

 given above ; several varieties in the collection of Mr. Stain forth 

 being variegated with rose, green and grey ; and one communicated 

 by Dr. Stanger, nearly white, with grey spots. (Soivb.} 



Habitat unknown. 



Chiton versicolor SQWB., Mag. of Nat. Hist., June, 1840, p. 292 ; 

 Conch. Illustr., f. 75 and f. 122 (var.). 



This seems to be an Ischnochiton of the fruticosus group, perhaps 

 the same as divergens Rve. ; but it has not been mentioned by later 

 authors, and the present location of the type is unknown. 



CHITON PLATYMERUS Sowerby. PI. 10, fig. 7. 



Shell ovate, scarcely keeled, slightly convex, smooth, of a dark 

 chestnut color ; marginal ligament coriaceous ; anterior and posterior 

 valves, and lateral arese of the middle valves obtusely radiately 

 ribbed; central arese of the middle valves longitudinally striated; 

 valves broad. (Sowb.). 



Habitat unknown. 



Chiton platymerus SOWB. in Zool. Capt. Beechey's Voyage, p. 149, 

 t. 41, f. 11. 



CHITON UNDULATUS Sowerby. PI. 10, fig. 20. 



Shell oblong, rather convex, slightly keeled, marginal ligament 

 coriaceous, undulated ; valves smooth, of a dull, pale, greenish- 

 brown, light brown in the center. The specimen appears to have 

 been worn. It is probable that small bunches of hairs existed on 

 the marginal ligament. (Sowb., in Zool. Capt. Beechey's Voyage, 

 p. 149, t. 41, f. 12). 



The recognition of this species is impossible without an examina- 

 tion of the original specimen, which is probably lost. It is not the 

 Ch. undulatus of Quoy and Gaimard. The habitat is unknown. 



CHITON ZONATUS Blainville. Body elongated, subcarinated \ 

 girdle moderate, covered with small tubercles, mealy. Shell of 8 

 valves entirely perfectly smooth ; the intermediates, the first larger 

 and as if trilobed in front, and unguiculate at the summit ; the others 

 increasing from the front backward, with the lateral areas indicated 

 by a carinated line. Color whitish gray, varied agreeably 



