104 
COELOSPLRA AUSTRALIS, Bp. IlOV. 
Description .—Dorsal valve nearly hemispherical, with a straight hinge¬ 
line, relatively high area, and widely rounded anterior border. The slightly 
convex surface is medially sulcate and ornamented with about eight broad, 
bifurcating riblets, the lateral ones strongly incurved in the median area. 
Both riblets and interspaces are marked with fine raised concentric threads. 
Ventral valve moderately convex, with about ten rounded or sub-acute 
riblets, bifurcating near the anterior margin, and crossed with concentric 
growth lines, which become slightly tegulate anteriorly. Spec. A : length, 
5 mm. ; width, 7'25 mm. Spec. B : length, 5 mm. ; width, 7 mm. 
Occurrence. —In calcareous Silurian shales, Mitta Mitta River. Also in 
dark mudstone, Co wombat, near Forest Hill, N.E. Gippsland. 
PRESENTED 
6 DEC1921 
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By Authority : Albert J. Mullett, Government Printer, Melbourne. 
