CHITON-RADSIA. 189 



This section or subgenus represents a further development of the 

 Acanthopleuroid characters which some Australasian species of the 

 restricted genus Chiton assume. In Ch. pellisserpentis, for example, 

 the mucro is median, the posterior teeth tend forward somewhat, the 

 sinus is smooth or only very obsoletely denticulate, and the girdle- 

 scales are striated and rather separated. In Sclerochiton the mucro 

 is slightly more posterior, the teeth slightly more tilted forward ; 

 the sinus is smooth, and the girdle scales still more separated. Ch. 

 pellisserpentis could be placed almost as well in Sclerochiton as in 

 Chiton s. s. ; the necessity of reducing Sclerochiton to the rank of a 

 section under Chiton will therefore be apparent. The girdle-scales 

 bear a certain resemblance to those of Enoplochiton, but this is a 

 purely accidental similarity, dependent upon their separation on the 

 surface of the girdle. 



C. MILES Carpenter, n. sp. PI. 46, figs. 1, 2, 3, 4, 5. 



Shell solid, rugose, oval, depressed, generally eroded; dorsal 

 ridge rounded, hardly defined; mucro behind the middle, nearly 

 flat ; apices of the valves prominent, obtuse. Ashen, spotted with 

 black-brown. Central areas transversely pretty regularly rugulose, 

 the wrinkles appressed ; lateral areas hardly elevated, moderately 

 well defined, conspicuously rugose, rugae subradiating, granose ; the 

 end valves similarly sculptured. 



Interior having the anterior valve with about 11, central 1, pos- 

 terior valve obscurely 9-11, slits. Teeth of posterior valves directed 

 forward, strongly callosed inside above the slits, sulcate outside ; 

 the rest of the valves having the teeth sulcate outside and pect- 

 inated at the margins. Eaves moderate, solid, deeply grooved. 

 Sinus deep, wide, wavy, smooth ; sutural laminse united. 



Girdle (pi. 46, fig. 1.) maculated, ornamented with large, solid, 

 more or less separated scales which are striated outside ; no hairs. 

 (Q>r.). Length 30, breadth 17J mill. ; divergence 130. 



Torres Straits (Mus. Cuming, no. 42.) 



A variety is described as being a little narrower, and blackish, 

 hardly maculated. 



Section KADSIA Gray. 



Radsia GRAY, P. Z. S. 1847, p. 126. Type Ch. barnesii. 

 Girdle and shell like Chiton, except that the insertion-plates of 

 the intermediate valves have two or several slits. 



