320 Transactions. 



struck off the New Zealand list. Having now read Lamarck's 

 diagnosis I fully agree with Mr. Hedley, and as Button's name 

 macilenta is available it has to take the place of erythrodon. 

 Webster's C. pura I do not consider as a distinct species ; the 

 radiate striation is more or less distinct in all specimens of C. 

 macilenta that came under my observation, and its greater 

 predominance, together with more regular concentric stria- 

 tion, can hardly be considered as sufficient reason why it should 

 be regarded as a species different from macilenta. Unfortu- 

 natelv, the Eev. Mr. Webster took the anterior for the posterior 

 margin, and the right for the left valve in consequence. 



Chiton huttoni, n. sp. Plate XVIII, figs. 1-6. 



General Appearance.— Shell oblong-ovate, angularly raised, 

 valves striated throughout, jugum smooth, girdle with rounded 

 scales; colour yellowish- olive, dull to dark green or brick-red; 

 interior whitish. 



The flatly convex anterior valve has seventeen to twenty- 

 four subequal riblets reaching to the apex, and broken up by 

 concentric rugae of growth ; sometimes a few riblets are inter- 

 spersed which do not extend to the apex ; the latter is smooth, 

 and mostly a little excavated posteriorly. 



The intermediate valves have the jugum smooth, projecting 

 a little behind ; the pleural tracts have about twenty to twenty- 

 five furrows on each side, which near the central area are narrow 

 and not deep, but usually widening and deepening on ap- 

 proaching the margin. Sometimes they are in breadth equal 

 to the riblets, but in some specimens they are narrower. They 

 extend the whole length of the pleural areas. The lateral areas 

 are strongly ribbed, the ribs broken up by the continuance 

 of the grooves on the pleural tracts. Their number is very 

 variable— the usual number is three to four, but sometimes as 

 many as five are found — and some of them may be divaricating, 

 which, however, is not the rule. 



The posterior valve has the mucro very little behind the 

 middle; the central area is flatly convex, with the same fur- 

 rows as the pleural tracts of the intermediate valves ; the pos- 

 terior slope is concave, and the posterior area has eighteen to 

 twenty strongly granose riblets reaching up to the apex. 



The girdle bears roundish medium-sized and compactly 

 imbricating polished scales, which under a powerful lens show 

 faint striation. 



The colour is very variable ; the most common is yellowish- 

 olive, then dull-green is met with, and one of these specimens 

 has the end valves blackish-green ; one specimen is brownish- 

 black, and one brick-red. The girdle has the same colour as 



