A small Patelloida was found among the shell-drift at .Michaelmas Cay, North Queensland, and later found alive on dead clamshells. In the Australian Museum I find the same species (unnamed) from Kawieng, New Ireland, hut the speeies seems hitherto to have been overlooked.

Shell elliptical, depressed, apex anterior, regularly ribbed, ribs twelve in number, rarely additional ones are developed, edge of shell uneven, strongly crenulate. Colour white, radially lined with brown, obscured in life by coralline growth, inside white, spatula marked with pale brown. Ribs smooth save for growth-lines. Length 14 mm.; breadth 9,5 mm.; height 4 mm. (type): largest specimen 19 x 14 x 6 mm.

Habitat: North Queensland (on the Great Barrier Reef).

I do not know any species that needs comparison. On the reef the form of Collisellina I discussed in the Proc. Zool. Soc. (Lond.) 1914, p. 670, was rarely met with but many specimens have been seen, and it must now be named. On aceount of further knowledge it is here specifically named as Collisella paropsis sp. nov., the type being selected from Michaelmas Cay, a dead shell measuring 30 mm. in Length, 28 mm. in breadth, and 9 mm. high. Much larger specimens occur up to 40 x 85 x 18 mm. The primary ribs number nine, secondary ones intercalating but never numbering many; anteriorly the species is narrowed with three prominent ribs, posteriorly broadening with tour stronger ribs, one on each side between these two series being slightly weaker; the ribs are elevated, sharply angular, white; the interspaces marked with black angulate patches; the margin is strongly cut by these ribs. Inside the shell is white, the edge darker, the spatula pale brown speckled with dark-brown spots, a blue tinge often present. The same species appears to occur on New Caledonia, but the" Philippine Island saccharina is easily separated by its shape, being seven-ribbed, the sides almost parallel. Quoy and Gaimards stellaris is nearer, but it hicks the narrowing of the Australian shell. I am now using Dall's name Collisellina (Amer. Journ. Conch., vol. vi, p. 254 1171) introduced for this group alone as tending to more exactitude in differentiating these difficult species.