44 PROCEEDINGS OF THK MALACOLOGICAL SOCIETY 



Posterior valve vrith tlie plate very sjiort and somewhat thrown 

 backward ; the slits, ten to twelve in number, are very irregular, 

 while the teeth are thick and coarsely pectinate. The girdle is covered 

 with medium size, ro\mded, a little separated, deeply grooved scales. 

 The grooves number five to seven on a scale. This description is 

 drawn up from a young shell, as old shells are too much eroded for 

 any sculpture to be determined, save the ends of the radial rows of 

 tubercles ; such are more elevated than younger shells. Length 

 of type 9, breadth 5 mm. Length of largest specimen 17"5, breadth 

 105 mm. 



Ilah. — Sunday Island, Kermadec Group. 



Statio7i. — In crevices of rocks between tides. " A Chiioti was 

 procured which had developed most peculiar habits; it lived in 

 crevices of rock between tide-marks, huddling together, half a dozen 

 being found one upon another, so that some did not touch the rock 

 at all. This species was entirely black, and allied to pellis-serpentis, 

 Q. & G." 



Hedley & Hull, having described Chiton funereiis from Lord Howe 

 Island and Norfolk Island, write : "A similar, if not identical, species 

 was found by Mr. T. Iredale on Raoul or Sunday Island, Kermadec 

 Group." I thinkthatin this case the words "if not identical" have 

 slipped in by accident, as my friends had my shell for comparison, 

 and there is only a slight superficial resemblance between the two. 



Sypharochiton themeropis diffei's from Ch. funereus in colour, shape, 

 sculpture, girdle-scales, and internal structure. S. themeropis is 

 a heavy crass shell, whilst Ch. funereus is a delicately formed species ; 

 the former is always dead black, the latter varies from black to light 

 brown, green, striped forms, etc. ; the former is a somewhat elongate 

 oval, the latter is a very broad oval ; in the former the anterior valve 

 is radially rowed with tubercles, the rows very distinct and widely 

 separated ; in the latter the tubercles are smaller, much more closely 

 packed, and no distinct rows appear ; in the former the jmstules on 

 the pleural areas of the median valves never show lineal arrange- 

 ment; in the latter this is generally the case. The girdle-scales in 

 <S. themeropis are deeply grooved with a few grooves ; in Ch. funereus 

 the girdle-scales are finely striate. 



The dissected specimens compared show that in this state no 

 confusion is possible ; in tlie Kermadec shell the insertion-plates are 

 comparatively long, with thick coarsely pectinated teeth, whilst in 

 Ch. funereus the insertion-plates are very degraded, with the teeth 

 very minute, and bearing very fine striae. The difi'erences are so 

 pronounced as to suggest that Ch.funerexis can scarcel}' rank in typical 

 Sypharochiton, whilst S. themeropis needs comparison with the type 

 of that genus, 8. themeropis can be readily distinguished from 

 <b\ pellis-serpentis (Q,uoy & Gaimard) by its smaller size, grooved girdle- 

 scales, and lack of longitudinal sculpture on the pleural areas of the 

 median valves. S. sinclairi (Gray) differs in its smooth pleural areas 

 and glossy girdle-scales of larger size. I always found this diagnostic 

 of this species when collecting, but have not seen it noted ; even when 

 the shell is eroded the glossy girdle-scales will distinguish it. 



