SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
the molluscs found time and material for forming a broad 
varix along the pallial border; whereas in sandy areas or under 
impure conditions of the water, as, for instance, in the presence 
of decaying crustacea and cephalopoda, seen in the Domain- 
road examples, the successive laminz were laid down closer 
together, and the shell itself would be proportionately thin and 
depauperated. 
This, together with another newly-described ornate species, 
P. producta, are among the commonest forms of the genus in the 
Victorian rocks. 
Affinities——P. victorie somewhat resembles the type ot 
shell described under the name of P. muta by J. Hall,* from the 
Hamilton Group of the State of N. york. P. muta difiers, 
however, from our species in having the beaks decidedly anterior, 
in the extremely lamellose condition of the main concentric 
strize, and in the absence of the concavely depressed escutcheon 
in the posterior region. 
Horizon and Locality—Silurian (Melbournian). From the 
Yarra Improvement Works, 8. Yarra, in blue and yellow shale, 
common; in the hard, dark shale of the Domain-road Sewerage 
Works at 103 ft. from surface, presented by Mr. F. P. Spry. 
In the yellowish sandstone with casts of shells, coll. Geol. Surv. 
Vict., Moonee Ponds Creek, Flemington; in the brown argil- 
laceous rock of Broadhurst’s Creek, east of Kilmore, coll. Geol. 
Surv. Vict., B® 18. In the brown argillaceous sandstone of 
Anderson’s Creek, near .Warrandyte, coll. Geol. Surv. Vict., 
B22; in the sandstone of Fraser’s, or No. 3, Creek, Springfield, 
coll. Geol. Surv. Vict., BP 25. [7915 (type), 7916-7.] 
Paleoneilo raricoste, sp. nov. Pl. II1., Fig. 50. 
Description.—Shell of variable size, length more than twice 
the height, elongate-ovate, rostrate. Depressed convex. 
Umbonal ridge not strongly developed. Anteriorly broad and 
well-rounded, the margin meeting the cardinal line at an obtuse 
angle; posteriorly produced and sharply rounded. Cardinal 
line arcuate, straight between the vertical line and the posterior 
angle. Beaks depressed. Teeth of hinge characteristic, but 
comparatively large and few. Greatest convexity of shell- 
surface just behind the anterior umbonal slope. Shell orna- 
mented with well-marked lamelliform concentric varices, com- 
paratively widely spaced, the area between each being relieved 
by numerous thread-like striz. 
* Paleont. N. York, Vol. V., Pt. I., 1885, Lamell. II. p. 337, Pl. XLIX.. Figs. 25-32. 
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