62 Proceedings of the Royal Society of Victoria. 



Measurements. 



Average height of zoarium, 20 ram. 



Average width of zoarium, 25 mm. 



Diameter of a zooecium with vestibule, "06 mm. 



Number of fenestrules in a length of 10 mm. = 11 to 13. 



Number of fenestrules in a width of 10 mm. = 14 to 17. 



Affinities. — This species is clearly allied to F. fossula, described 

 by Lonsdale from the Carbo-permian of New South Wales and 

 Tasmania.^ The latter differs however, in the smaller number of 

 the zooecia, in their more or less parallel arrangement, in the 

 apparent absence of a prominent vestibule (Lonsdale's tig. 1. being 

 that of a cast from the celluliferous face), and in the sub-rect- 

 angular or long elliptical form of the fenestrules. The zoarium of 

 F. fossula attains to a much larger size than F. margaritifera. 



In its prominent zooecia, and the tuberculated carinae the 

 present species belongs to the type of F. retiformis, Schlotheim. 



Occurrence. — F. mai'garitifera appears to be of frequent 

 occurrence (judging by the relative proportion of associated 

 fossils, in the small collection in the National Museum from the 

 localities cited) at the junction of the Worri-Yallock and Yarra, 

 Oeol. Surv. Victoria, B 23 [587-8J ; and at Yering, Upper Yarra, 

 Oeol. Surv. Victoria [592-5]. 



The matrix in which these fossils occur is an ochreous and 

 somewhat indurated clay. The fossils are represented chiefly as 

 casts ; in some instances, however, the original structure of the 

 fossil is preserved. 



Horizon.- — Highest beds of the Silurian (Yeringian). 



Note. — In Smyth's Progress Report, Geol. Surv. Victoria, 

 1874, p. 34, Sir F. McCoy recorded two new species of Fenestella 

 from the Upper Yarra District. Up to the present, the above 

 species is the only new form which the writer has been able to 

 discover in the Survey collections from that locality. 



Fenestella austral is, sp. nov. (PI. X., Fig. 11). 



Specific characters. — Zoarium funnel-shaped, somewhat elongate; 

 surface undulate. Inner surface with circular, open zooecia 



1 In Strzelecki's Phys. Descr. New South Wales, 1845, p. 26!), pi. ix., fij^.s. 1, la. 



