193 



one or more patelliform parasites. I thought, naturally, 

 they were young individuals of the same species, but they 

 proved to be always examples of what I have named and 

 described as Acmcea patellavecta. 



Patella axiaerata, n. sp. PL xv., figs. 3 and 4. 



Shell small, depressed, conical, elliptical, apex somewhat 

 antemedian, lateral margins somewhat concave, so as to be 

 lifted off a flat surface. Apex blunt, surface smooth ; colour 

 opaque- white, numerous rays (18 in the type), golden- 

 yellow, with darker golden axial hairlines in them. Margin 

 simple, smooth. Spatula well marked, large, with a distinct 

 neck and large head. Interior white, through which the 

 yellow rays are visible. 



Dimensions. — Length, 4*4 mm. ; breadth, 3*2 mm. ; 

 height, 1*9 mm. 



Habitat. — Type, Rottnest Island, with many others; 

 King George Sound beach, 8 small. 



Variations. — Some are shorter and higher, more convex 

 in the hinder slope, more acute at the apex. The number 

 of golden rays may be only 12 or 10, due to the fusion of two 

 narrower into a larger one; sometimes the ray, which is at 

 first single, becomes later double. In some examples the 

 golden hairlines in the rays are conspicuous and numerous. 

 The apical region inside, for a varying extent, may be of a 

 yellowish-brown colour. 



The shape of its base suggests that its usual habitat is 

 the conical surface of another shell, and as this is a very 

 common habit with Acmcea, it may belong to this genus. It 

 recalls Patella illibrata, Verco, by its form and apex and 

 rays. It was not taken alive. 



Type is in my cabinet. 



Patella ustulata, Reeve. 



Patella ustulata, Reeve, Verco, Trans. Roy. Soc, S.A., 1906, 

 vol. xxx., p. 206; 1907, vol. xxxi., p. 99; and 1912, vol. 

 xxxvi., p. 182. 



This was taken at Esperance Bay and King George 

 Sound; at Ellensbrook up to 25 mm. long, by 20 mm. wide, 

 by 7 mm. high, the largest specimen taken in the West; at 

 Yallingup and at Bunbury, up to 18 mm. long. 



They vary greatly. A common form has from 12 to 14 

 broad white or yellow ribs ; the rest of the shell may be white 

 or yellow or black or pinkish-brown. Some, after a moderate 

 growth in this fashion, become wholly black. 



They do not reach the size of those at Beachport, which 

 may be 47 mm. by 40 mm. 



