95 
thousand miles of coastline, but going out from Murat Bay 
to St. Francis Island (Nuyts Archipelago), a distance of 
40 miles, Plaxtphora costata, Blain, formerly known as P. 
glauca, Q. et G., takes the place of P. albida, and specimens 
of P. cestata were found in Western Australian waters. P. 
albida, Blain., is generally found on or above high-water 
mark in South Australia, but on the Western Australian 
‘coast its place is taken by Livlophura georgiana, Q. et G. 
These could be frequently seen on exposed rocks. The order 
of exposure in South Australian waters, mutatis mutandis, 
is P. albida, on exposed rocks at or near high-water mark; 
I. crispus, in abundance everywhere, in sheltered pools, a 
foot or two below, with Acanthochites on sandy moss-covered 
rocks. In deeper pools, Z. contractus, I. cariosus, I. ustu- 
latus, I. smaraydinus, and other Ischnochitonidw, and deeper 
still in 2 or 3 ft. of water at low tide, the true chitons, 
jugosus, tricostalis, exoptandus, and calliozona. On the west 
side of St. Vincent’s Gulf I have found the true chitons on 
exposed rocks in shallow pools. 
The order in which Western Australian chitons are found 
is Liolophura georgiana, near or above high-water mark (P. 
albida and I. crispus are missing), and on account of the 
‘small fall of the tides Chitons, Callochitons, and Ischnochitons 
may be found together. The Jschnochitonide favour shallow 
pools, while the true chitons prefer the ocean surf. 
Chiton torrianus was found in Western Australia on the 
under-side of wholly exposed rocks. This chiton, formerly 
misnamed cox?, was separated by Hedley and Hull as C. 
torrt, afterwards altered to ftorrianus. It was rarely found 
in South Australian waters till Mr. Walter Klem, of Corney 
Point, Yorke Peninsula, discovered a number. In Western 
Australia it was found in almost every place visited. 
It is hoped that this first paper on Western Australian 
Polyplacophora may do something to stimulate and help 
future beginners at chiton-hunting in Western Australia. 
My acknowledgments are due to Mr. W. T. Bednall, 
whose excellent paper on South Australian Polyplacophora, 
Proc. Mal. Soc., London, vol. ii., part iv., April, 1897, has 
been the foundation of much of my work, and to whose 
paper I have had frequently to refer; also to Mr. M. M. 
Maughan, B.A., for his kindly revision of my paper and his 
assistance in examining my new species and verifying some 
of my descriptions. 
1. CALLOCHITON PLATESSA, Gould, 1846. F SST AAYS 
Chiton platessa, Gould, Proc. Bost. Soc., N.H. II., 1846, 
p. 143; Pilsbry, Man. Conch., ser. i., vol. xiv., p. 49. — 
