52 



for 1876, p. 50, 1877 (animal). P. alticostata AD. & ANGAS, P. Z. 

 S. 1865, p. 56, t. 2, f. 11. Patella costata ANGAS, P. Z. S. 1867, 

 p. 221. 



A very variable form in sculpture and coloration. The outside 

 is dull, usually corroded; rubbed specimens which have black 

 scallops on the border show narrow lunate black markings in the 

 spaces between the ribs. 



Figures 72, 73 are Angas's alticostata ; the other figures are 

 drawn from specimens before me. 



A. MARMORATA Tenison-Woods. PL 42, figs. 66-70. 



Shell irregularly ovate, low-conical, the apex eroded, at about the 

 anterior third. Surface dull, eroded, having 7 to 10 wide ribs, often 

 sub-obsolete. The ribs are light, interstices dull black ; edge of the 

 shell irregular. 



Inside having black stripes between the ribs, which are indicated 

 by light stripes; central area yellowish-brown, closely dotted or 

 marbled with black. There is a snow-white line just within the 

 muscle-scar. Length 15, breadth 13, alt. 5 mill. 



Tasmania ; Port Jackson, N. S. Wales, Australia. 



Acmcea marmorata TENISON-WOOD, Proc. & Rep. Roy. Soc. Tasm. 

 for 1875, p. 156, 1876 ; Ibid. 1876, p. 53, 1877. 



May be known at once by the peculiarly dotted, marbled interior. 

 There is a variety which may be called submarmorata, in which the 

 inside is not distinctly radiately striped around the central area, 

 the white line within the muscle-impression is narrow or obsolete, 

 and the outer surface has numerous rather narrow riblets in place of 

 the few wide ribs of the typical form. This variety is from Port 

 Jackson. It is represented on pi. 42, figs. 69, 70. 



A. RUGOSA Quoy & Gaimard. PI. 37, figs. 5, 6. 



Shell ovate, conic, with radiating rugose unequal ribs; margin 

 crenulated ; broadest behind ; apex sub-median, acute; inside bluish, 

 border and center blackish-chestnut. 



Length 16, breadth 12, alt. 6 mill. (.) 



Amboyna. 



PateUoida rugosa Q. & G., Astrol. p. 366, t. 71, f. 36, 37. 



Compare A. lacunosa Rve. 

 A. LACUNOSA Reeve. PL 37, figs. 7, 8, 9, 10, 11. 



Shell small, oblong, apex near the front third, or nearer the mid- 

 dle ; 'surface dull, lusterless, rough and irregular, having 18 to 24 



