16 



placed in rings, x 65 ; this ring resolves itself into a string 

 of blunt-ended scales, set in a circle. Owing to the minute 

 nature of these scales the general appearance of the girdle, 

 except under a high power, is spongy. The sutural tufts are 

 white and well defined. 



Dorsal area. — Broadly wedge-shaped. In typical shells it 

 is ornamented with longitudinal rows of strongly-raised cir- 

 cular pustules, set bilaterally in divergent lines, thus forming 

 a V with the apex in the centre of the area. But in different 

 specimens these pustules vary from circular, well-raised 

 pustules to those that are mitre-shaped, or even to long flat 

 dashes. Again, in some specimens this area is absolutely 

 smooth except in the margins, but this variation appears 

 somewhat rare. 



Pleural and lateral areas. — These, in typical specimens, 

 are not distinctly differentiated and are ornamented with 

 longitudinal rows of strongly- raised circular pustules, gradu- 

 ally increasing in size towards the girdle. The varient, which 

 I suggest should be known as variety pustulosus, Ashby, has 

 the first row or so of pustules from the dorsal area, more or 

 less round, but fully half the valve is decorated with a few 

 large tear-drop-shaped pustules, some of them being fully 

 three or four times as long as wide. In some, the regularity 

 of the longitudinal rows is preserved; in others, this system 

 of sculpture is lost, these tear-drop pustules being irregularly 

 placed, widely separated, and very raised. 



Colcnir. — While most specimens are mottled pale green 

 and black, there are some that are pale green throughout, 

 and others that are uniformly rufous; in some the dorsal area 

 only is reddish-brown, in others it is pink. When disarticu- 

 lated and cleaned the shells are transparent and, usually, both 

 tegmentum and articulamentum are green. 



Habitat. — While very numerous at Port Jackson, New 

 South Wales, it appears less common in Victoria, and I have 

 not taken it in South Australia, where its place is taken by 

 the allied form, A. kimheri, Torr. This latter I also met with 

 in Western Australia. 



Probably the Sydney shell has extended down the east 

 coast and then turned towards the west, along the Victorian 

 coast; the allied form, A . kimberi, has come in from the west 

 and somewhat overlaps A. retrojectus in Victoria. 



I am indebted to Messrs. Gatliff and Gabriel for the 

 opportunity of examining a number of specimens from their 

 respective collections. 



They were from Western Port, Port Philip Head, Point 

 Nepean, Torquay, and San Remo, all in Victoria. They show 



