104 



28. ACANTHOCHITES SUBVIRIDIS, Sp. 710V, 



Plate xxv., figs. 3a,b,c,d,e,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 costae 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 latero-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 Gryptoplax Gunnii. 



Measurement. Length, 22 mm. : breadth, 12 mm. 



Habitat. Four specimens from Rabbit Island, Albany. 



Remarks. I was very much inclined to place this speci- 

 men under A. costatus, Ad. and Ang., Pilsbry, Man. Conch., 

 ser. i., 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 E. A. Smithy 

 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. 



29. TONICIA HULLIANUS, Sp. UOV. 



Plate xxv., figs. 4a,b,c,d,e,f. 

 General Appearance. Shell elliptical, broad, smooth,, 

 back rounded, side slopes curved, valves distinctly beakecL 



