104 
28. ACANTHOCHITES SUBVIRIDIS, sp. nov. 
Plate xxv., figs. 3a,b,c,d,¢,f. 
General Appearance. Shell elongated, narrow, carin-~ 
ated, side slopes curved. Colour creamy-white with a pale- 
green tint on some of the valves, a brighter green on the 
dorsal area with a pink-tipped beak in some specimens; girdle 
dark-buff. 
Anterior Valve. Strongly marked with fine granulose, 
radiating cost corresponding to the five slit rays. The 
sutural plates are much larger than the tegmentum. Inter- 
nally milky-white with a curved sutural band. 
Posterior Valve. Distinctly marked with dorsal and 
latero-pleural areas. The dorsal area is a smooth ridge, 
irregularly transversely striated, terminating in fine radial 
riblets, which are continued in the sutural plates as slit rays. 
The letero-pleural area is covered with squamose granules. 
Sutural plates large, sinus wide. 
Median Valve. Dorsal and latero-pleural areas same as. 
posterior valve with the exception of two postmedian granu- 
lose radial riblets, one on the anterior margin. In some 
specimens these riblets are strongly pustulose, small at the 
apex, and increasing in size toward the margin. Internally 
one slit ray, sutural plates large, sinus medium. The dorsal 
area is a pale-green colour, with in some cases a pink tip. 
In others it is a dark-buff. 
Girdle. Leathery, very broad, 7 sutural tufts on each 
side, and 4 round the anterior valve. Elementary spicules 
may be seen in one or two. Colour dark-buff, resembling the. 
girdle of Cryptoplax Gunnit. 
Measurement. Length, 22 mm.; breadth, 12 mm. 
Habitat. Four specimens from Rabbit Island, Albany. 
Remarks. JT was very much inclined to place this speci- 
men under 4. costatus, Ad. and Ang., Pilsbry, Man. Conch..,, 
ser. 1., vol. xiv., p. 40, but the distinctly pustulose riblets 
and coloured dorsal areas with other minor differences have 
led me to place it under a new species. Adams and Angas” 
drawing of A. costatus gives a very diminutive riblet. The 
minute fringe of white spicules, described by EH. A. Smith, 
Zool. Coll. “Alert,” p. 83, t. 6, f. F., as Chiton (Macan- 
drellus) costatus, is absent in all the specimens. The greenish. 
tint so common has given its name, subviridis. se 
f = yf re 7 yFF) PEE | 
29. ont fe bt och Len fe ; 
Plate xxv., figs. ja,b,c,d,e,f. FS53-G 
General Appearance. Shell elliptical, broad, smooth,. 
back rounded, side slopes curved, valves distinctly beaked. 

