202 Bulletin, Vanderbilt Marine Museum, Vol. IV 



Material examined: Six specimens, Wafer Bay, Cocos Island, 

 March 5, 1926. Seven very large specimens, "Wafer Bay, Cocos Island, 

 February 4, 1928; all collected by the "Ara." 



Color: Olive-black, blackish, or brownish dorsally, dappled with 

 olive, with a transverse olive-green stripe on each side of the keel. 

 With transverse ziczac lines of light blue, six on each side of the 

 seven posterior valves. Girdle mottled green. Interior white, each 

 valve with a pair of median rays and a central spot of brown. 



Technical description : Shell large, heavy, widely oval, moderately 

 elevated and moderately carinated, with the lateral slopes nearly 

 straight or but little convex ; entire surface nearly smooth. 



Measurements : 120 mm. long diameter ; 72 mm. short diameter. 



Anterior valve : Regularly convex, devoid of sculpture, except ex- 

 ceedingly minute granulations and with several concentric lines of 

 growth arrest. Twenty-six slits present. 



Intermediate valves: The central areas of these valves are sepa- 

 rated by an obtuse blunt carina from the lateral areas; there is no 

 sculpture except very fine lines indicating growth arrest. Two or 

 three slits are present in each valve. 



Posterior valve: With the umbo extremely close to the anterior 

 margin; the postlateral region rounded, sloping. Twenty-six slits 

 present. 



The sutural plates are broad, the sinus somewhat shallow, with 

 eight teeth. 



Girdle: 12 mm. wide (preserved specimen), strong, composed of 



olivaceous blackish, imbricating scales, each of which has the dorsal 



surface a little convex. 



References: Chiton goodallii Broderip, Proc. Zool. Soc. London, 

 1832, p. 25.— Tryon, Man. Conch., vol. XIV, p. 191, pi. 29, figs. 9, 

 18.— Stearns, Proc. U. S. Nat. Mus., vol. 16, p. 404, 1893 (issued 

 1894).— D all, ibid, vol. 37, p. 247, 1909. 



Chiton goodalli Sowerby, Conch. Illus., figs. 34, 40. 



Chiton goodalli Reeve, Conch. Icon. fig. 8. 



Radsia goodalli Carpenter, Mss. 



Chiton (Radsia) sulcatus Sowerby. 

 Plate 127. 



Type: Wood states: "This rugged Chiton is said to inhabit the 

 South Seas." Depository not stated. 



