88 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Chiton pallidiis, Eeeve : Conch. Icon., pi. xvi, fig. 92, March, 1847. 

 Ischnochiton pallidiis, Eeeve : Pilsbry, Man. Conch., ser. I, vol. xiv, 

 p. 89, pi. xxiii, fig. 91. 



There is a nice scries of this species. I have carefully compared 

 the original tablets in the British Museum, and am unable to separate 

 /. contractus and /. pallidus. 



8. IscHNocniTON usTULATTJS (Eecvc). 



Chiton ustulatus, Eeeve: Conch. Icon., pi. xvii, fig. 102, March, 1847. 

 Lepidopleurus ustulatus, Eeeve: Angas, Proc. Zool. Soc. 1867, p. 222. 

 Ischnochiton ustulatiis, Eeeve: Pilsbry, Man. Conch., ser. I, vol. xiv, 

 p. 96, pi. xxiv, figs. 100," 1-4, 11, 12. 



One specimen only. The valve slits are as follows: head-valve, 13; 

 median, 1 ; tail-valve, 16. Some of those in the tail-valve seem to 

 be caused by the splitting up of the slits, and probably the normal 

 number is less than in the specimen examined. Both in the head- and 

 tail-valve they are at very unequal distances apart. The interior of 

 the valves is of a bluish colour near the slits, but becomes of a reddish 

 hue towards the beaks. 



9. IscHNOCHiTOjsr (Haploplax) pura, n.sp. PI. VI, Pigs. 3, Sa. 



Shell elongate-oval, elevated, carinate. Surface smooth to the 

 naked eye, but granular under a lens. Colour of valves nearly white, 

 sometimes showing a faint trace of yellow. Girdle yellow-brown. 

 The intermediate valves have straight sutures. The lateral areas are 

 raised, and are separated from the median ones by a distinct diagonal. 

 The sculpture over the whole of the valves is minutely granular, 

 and in worn specimens has the effect of a series of pits. This 

 sculpture continues right over the central carina. Valve viii is 

 somewhat produced posteriorly, and has a projecting mucro a little 

 behind its centre. The interior of the valves is of a whitish colour. 

 There ai"e eleven slits in the posterior valve, and the teeth are short : 

 these latter are much larger in the anterior valve, where they number 

 ten. The median valves have one slit each side, as iisual in tlie true 

 Ischnochiton group. The girdle-scales are yellowish, very small, and 

 smooth. Length about 18 mm., breadth about 7 mm. 



This interesting species, which appears to belong to the recently 

 described ' section Jlaploplax, does not possess any striking charac- 

 teristics. It is very difficult to say whether a surface such as this 

 shell has is really "punctate" or "granulate." This difficulty 

 Mr. Pilsbry seems to have felt, as in the Manual of Conchology he 

 has allowed the description of /. smaragdinus, Angas, to stand "most 

 minutely punctured" ; while he subsequently has made it the type of 

 his section Haploplax, which is cliaracterized as having the surface 

 " smooth, except for minute granulation." Perhaps the shell will be 



» rilsl)ry, rruc. Acad. Nat. Sci. riiilad. 1894, p. 71. 



