124 THE FRESHWATER MOLLUSCA OF VICTORIA 
Family ANCYLIDAE 
Genus ANCYLUS Geoffroy 1767. 
Ancylus australicus Tate. 
(PL III, Figs. 31, 31a). 
1880 Ancylus Australicus Tate, Tr. Roy. Soc. S. Aust., iii, p. 102, pi. 4, 
figs. 4a-b. 
1882 Id. Tate and Brazier, Pr. Linn. Soc. N.S.W., vi, p. 559. 
1882 Id. Smith, Journ. Linn. Soc. Lond., Zool., xvi, p. 297, pi. 7, 
figs. 36, 37. 
1893 Id. Billinghurst, Viet. Nat., x, p. 63. 
1896 Id. Tate, Rept. Horn Exp., Zool., ii, p. 216. 
1917 Id. Odhner, K. Sv. Vet. Ak. Handl., Hi, (16), p. 74. 
1917 Id. Cherry, “Bilharziosis,” p. 4, figs. 12, 12a. 
1932 Id. Cotton and Godfrey, S. Aust. Nat., xiii. No. 4, p. 164, pi. 3, 
fig. 11. 
1936 Id. Cotton, S. Aust. Nat., xvii. Nos. 1-4, p. 84, fig. 41. 
Size of moderately large example. — Length, 4 mm. ; 
breadth, 2 5 nmi., height 15 mm. 
Localities.— Melhourae (Tate); Frankston (J. A. Ker- 
shaw) ; Alphington, Melbourne Botanic Gardens ( J . Searle) ; 
Lake Wendouree, Meredith (J. H. Young) ; Blackburn Lake 
(A. L. McLachlan) ; Tarraville (T. Worcester) ; Castlemaine, 
Studley Park (C. J. Gabriel). 
Vernacular Name . — Freshwater Limpet. 
Observations. — This, our commonest freshwater Limpet, is 
usually found on the under surface of floating leaves. The 
shell is pale, thin and delicate; conic depressed, lengthened; 
sides subrectilinear or slightly convex, diverging slightly 
forwards; apex blunt post median, with about two-fifths of 
the shell behind it, inclining backwards, and directed towards 
the right ; the line from the apex to posterior border slightly 
concave, to the anterior border almost rectilinear ; peritreme 
oval, distinctly narrowed posteriorly. It has a wide dis- 
tribution, being recorded in South and Central Australia 
and as far north as Arnheim Land. Odhner, recording it 
from the Fitzroy River, remarks: “The position of the apex 
is somewhat variable inasmuch as it may be nearly medium 
or more distinctly to the right; it is always situated at the 
posterior third of the shell. The anterior slope is a little 
more convex than in the figures of E. A. Smith (op. cit.), the 
shells a trifle more depressed and the apex directed to the 
right (not to the left as in the figures).” 
