IKEDALE : THE CHITONS OF THE KERMADEC ISLANDS. 43 



Ch, (Breiis, Reeve, from New Zealand. Hedley & Hull (Rec. Austr. 

 Mus., vol. vii, p. 261, 1909) described Ch. vmiclusensis from Port 

 Jackson, which, though they did not note it, might have heen com- 

 pared with Ch. canaliciilatus, Qiioy & Gaimard, but neither much recall 

 the present species or Ch. coryphetis, Hedley & Hull. 



The Kermadec species I have called exasperata on account of the 

 variability of the shells, and my inability to account for it. It is 

 very close indeed to Ch. corypheus, Hedley & Hull, but superficially 

 the Kermadec shell has the ribbing on the anterior and posterior 

 valves less nodulous, which is also the case with the lateral area 

 sculpture of the median valves. Closer examination shows the scales 

 on the girdle to be smaller in the Kermadec species, whilst the sulci 

 on the pleural areas of the median valves are weaker. Internally, as 

 was anticipated, little distinction can be seen, but the sinus in the 

 Kermadec shells is noticeably narrower. I should consider that veiy 

 probably these two are only subspecifically distinct, but, as I am 

 continuing my investigations into this group, I am introducing my 

 Kermadec shell as a species. Fiom Ch. cereun. Reeve, my Kermadec 

 species is easily separated by its much less size, much smaller 

 girdle-scales, more closely spaced sulci on the pleural ai-eas of the 

 median valves, etc. Ch. discolor, Souverbie, is also a large species, 

 whilst Ch. suteri, Iredale, from New Zealand, has widely spaced 

 sulci and (/lossy girdle-scales. 



Genus SrPHARocHiTON. 

 Sypharochiton, Thiele, Das Gebiss <ier Schnecken, vol. ii, p. .'365, 1893. 

 Type (by monotypy). Chiton pellis-serpentis. Quoy & Gaimard. 



Syphakochiton themeropis, n.sp. PI. II, Fig. 14. 



Shell small, oval, elevated, keeled, side slopes almost straiglit, 

 valves beaked, girdle scaly. Colour black ; majority of specimens 

 considerably eroded. Anterior valve with sixteen to twenty strictly 

 ladial rows of separated tubercles, the intervals minutely pustulose, 

 the pustules being flat-topped and circular. Median valves with their 

 lateral areas showing three or four separated tuberculose radial rows, 

 the intervals pustulose ; the pleural areas regularly pustulose, with 

 no arrangement whatever into longitudinal rows. Posterior valve witli 

 the mucro elevate, sub-central, slightly anterior, the posterior slope 

 faintly convex. The anterior portion is sculptured as the pleural 

 areas of the median valves, the posterior as the anterior valve with 

 few strictly radial rows of separated tubercles. Inside coloration 

 dark blue-green. Insertion-plate of anterior valve with ten to twelve 

 slits, the teeth coarsely pectinated and thick; the plate short, but 

 somewhat projecting, and the slits irregular. Teeth pale green. 

 Median valves have the insertion-plate one-slit, the posterior tooth 

 short and stopping very abruptly before reaching the lateral edge of 

 the valve. The sutural laminae are pale gi-een, rounded, low, and 

 widely separated; tlie tegmentum generally approaches between, but, 

 when the plate is recognizable, it is seen to be strongly denticulate. 



