New or Little-knoivn Victorian Fossils. 73 



Vet. Akad. Haadlingar, p. 109, pi. i. fig. 4. Davidson, 1871, 

 Brit. Sil. Brach., No. 4 (Pal. Soc. Mon.), p. 318, pi. xlviii., figs. 

 1-9. 



The convex pedicle valve of our specimen is not so strongly 

 globose as that of typical specimens, but in other respects it is 

 quite comparable with the European and American examples. 

 The valve is relieved by eleven fine but distinct and ridgelike 

 radii, between which the shell surface is crossed by about 8-10 

 very fine radiating lines. 



Measurements. 

 About 12 mm. long; 14 mm. wide. 



Observation. — P. transversalis is a well-defined and common 

 form in the Niagara group of North America, and in the Silurian 

 (Gotlandian) of the British Islands, the continent of Europe 

 (Norway and Bohemia), and the Island of Gotland. 



Occurretice. — In dark bluish limestone. Deep Creek, seven 

 miles S.W. of Walhalla, Gippsland. Presented by Rev. A. W. 

 Cresswell, M.A. [668]. 



Horizon. — Silurian (Yeringian). 



Plectambonites cresswelli, sp. nov. (Pi. XL, Figs. 8-10). 



Characters of the ventral valve. — Outline nearly semi-circular, 

 hinge line straight, but little transgressed by the umbo ; cardinal 

 extremities angular and not much produced. Sub-globose, nearly 

 as deep as P. transversalis. Surface with about eleven distinct, 

 threadlike radii, the spaces between the riblets occupied by about 

 9-12 fine parallel striae. The intercostal surface undulate, the 

 depressions curved, concave anteriorly, and at somewhat equi- 

 distant intervals, those on the highest part of the \alve about 

 .3 mm. apart. 



Measurements. 

 Approximate, as the valve is slightly imperfect. 

 Length . - - - ,5.5 mm. 

 Width - - - - 9 „ 

 Depth of ventral valve - 2.5 „ 



