70 Proceedings of the Royal Society of Victoria. 



surface of attachment. Surface of valves concentrically undulate, 

 finely lineated radially from the umbo to the anterior margin ; 

 between the radii, the surface upon magnification is seen to be 

 traversed by numerous excessively tine striae. Shell structure, 

 seen in partially decorticated specimens, coarsely punctate. 



Measurements. 

 A large specimen - - width 44 mm. 



length 23 „ 

 Another specimen - - width 28 ,, 



length 16 ,, 



Affinities. — In outline our species is rather like Stropheodonta 

 ornatella, Davidson sp. (Salter MS.)\ but the latter has longer 

 valves, and the extremities of the cardinal margin are not so 

 acuminate. The two forms also differ in the character of the 

 surface striae, S. ornatella having them much coarser in the form 

 of primary and secondary riblets. 



Another closely related form, and one typical of the sub-genus 

 is Stropheodonta (Leptostrophia) tilosa, Sowerby sp., of the 

 Wenlockian and Gotlandian in Europe'-; especially with regard 

 to its fine ornamentation of radii. The latter species however 

 has the cardinal extremities much less produced, is proportion- 

 ately longer, and the primary radii are far more numerous. 



Occurrence. — North of Lilydale. Specimens presented by the 

 Rev. A. W. Cresswell, M.A. [665-6] ; [659] ; [1421]. Also Geol. 

 Surv. Vict. B 23, Junction of Woori Yallock and Yarra [657-8]. 

 In both cases the specimens occur in a kind of ochreous mudstone, 

 the rock in the latter instance being much more indurated. 



Horizon. — Silurian (Yeringian). 



Sub-genus Brachyprion, Shaler. 



Stropheodonta (Brachyppion) lilydalensis, sp. nov. 



(PI. XL, Fig. 5). 

 Specific characters. — Shell semi-circular, broadly rounded anter- 

 iorly, with the cardinal extremities somewhat produced and 



1 Strophomena ornatella (Salter MS.) Davidson, 1871, Brit. Sil. Brachiopoda (Pal. See. 

 Men.). No. 4, p. 300, pi. xliii., fi'js. 10-20. 



2 Orthis filosa, Sowerby, 1839, in Murchison's Siluriati System, pi. xiii., fig-. 12; Stropho- 

 mena filosa, Sow., sp .Davidson, 1871, Brit. Sil. Bracli., No. 4. p. 307, pi. xliv. fl>;;i. 14-20. 

 Stropheodonta (Leptostrophia) filosa, Sow. sp.. Hall and Clarke, 1S92, Paleontology of New- 

 York, Brachiopoda, pt. i. p. 288. 



