167 



58." Acanthochites rufus, sp. H ov. PI. vi., tigs. 4a-/. 



General A ppearance.— Elliptical, roundedly arched, 

 much more so than A. variabilis, yalves beaked, colour uni- 

 formly terra-cotta. 



Anterior Valve. — Five very indistinct riblets, which are 

 really waves in the pustules. The pustules are in regular 

 lines, appearing continuous with those on the second valve. 



Median Valve. — Covered with pustules arranged in 

 longitudinal lirse. There is little difference between .the 

 dorsal, lateral, and pleural areas. There are about twelve 

 rows of these pustules on the latero-pleural area divided by 

 sulci, and about fourteen rows on what may be termed the 

 dorsal area. The microscopic pustules in these are much 

 smaller than those in the latero-pleural areas. There is a 

 gradual elevation towards the posterior end of each valve, 

 and the pustules in this lateral region are more irregular. 



Posterior Valve. — Mucro very indistinct, post median. 

 A deep sulcus parallel to the girdle separates it from the 

 outer edge of the shell. Rows of pustules converge towards 

 the mucro and appear continuous with the rows on the 

 median valves. Nine rows on the latero-pleural areas and 

 twelve on the dorsal areas. The mucro is almost at right 

 angles to the girdle, and the rows of pustules are concentric 

 below the mucro. 



Girdle. — Leathery, very narrow in dried specimen, covered 

 with spinelets. Five corneous spots on the girdle surround- 

 ing the anterior valve and one at each suture, very indis- 

 tinct in some. 



Measurement . — 10 x 5 mm. 



Hob. — One specimen only from Kangaroo Island. 



Remarks. — The detailed description of this shell ap- 

 proaches A . variabilis, but the absence of the distinction 

 between the dorsal and the latero-pleural areas and the 

 marked difference in the appearance and shape of the shells 

 when placed side by side make it necessary to place it in a 

 new species. 



The name rufus is given on account of its rich terra- 

 cotta- colour. 



59 Acanthochites kimberi, sp. nov. PI. vi., rigs. 5a-f. 

 General Appearance. — Long, narrow, tapering towards 

 the ends. Valves rounded, beaked. Colour. — Either cream 

 with splashes of dark- and light-green or, in some specimens, 

 the green predominating over the cream with splashes of 

 pink on some valves. 



