278 



Girdle. — Glothod with minute, imbricating, flat, highly- 

 polished scales, apparently smooth, but under 65 mag. there 

 is a suggestion of fine scratching. The scales are mostly the 

 same orange colour as the rest of the shell, but a few al-e 

 buff-orang«. The scales remind one of minute, thin, rounded- 

 edged biscuits with the sides uppermost. I can see no girdle 

 fringe on the type, but there is one present in the juvenile 

 specimen collected at Venus Bay. 



Measurements. — Type a little more than 8x4 mm., the 

 para-type 9 x 4J mm., girdle rather incurved. 



Hah. — Two specimens collected by myself at Marino, 

 South Australia, and one only, 4J mm. in length, I collected 

 *at Venus Bay in February, 1910. 



In Conclusion. — This is evidently a rare species; the only 

 striking general characteristic is its rich orange colour and 

 highly- polished surface. It is easily confused with juvenile 

 Heterozona cariosus, Pilsbry, but the scales in that species 

 are larger and definitely ribbed. The smallness of the scales, 

 as well as their being unribbed, will separate it from juveniles 

 of lineolatus, Blainville, and lincolnensis, Ashby, and 

 whereas I. torri, Ire. and May, has scales about as small they 

 are always striated, and the shell of this latter is rounded, not 

 sub-carinated. 



IscHNOCHiTON (Heterozona) properensis, n. sp. 



General Appearance. — Dingy brown, about twice as long 

 as broad, sub-carinated, flat, side slope slightly rounded, 

 coarsely decussated, and lateral areas concentrically ribbed. 



Colour.- — More or less Saccardo's umber all over (Ridg- 

 way's Colour Standards, pi. xxix.). 



Anterior Valve. — Upper fourth, finely decussated, radially 

 ribbed with about forty closely-packed, broken ribs, several 

 clearly-marked growth-lines in evidence, becoming more raised 

 towards the outer margin. 



Posterior Valve. — The anterior portion definitely separ- 

 ated from the rest by diagonal lines; this portion, as well 

 as that immediately below the mucro, strongly decussated or 

 granulose, the posterior portion concentrically ribbed with 

 four rows of coarse pustules, remarkably regular, and looking 

 like a string of beads. 



Median Valves. — Lateral areas raised, concentrically 

 ribbed with about 10 strongly-raised ribs which are broken by 

 about 8, fairly deep, equidistant, radial grooves, with the 

 result that the concentric ribs are broken into coarse, squarish 

 pustules. Pleural and dorsal areas are coarsely decussated 

 with a system of closely-packed flatish pustules. 



