A MONOGRAPH OP THE TERTIARY POLTZOA OP VICTORIA. 55 



M. Clarkei in Monoporella, a genus to which, as originally defined by Hincks 

 (A.M.N.H., July, 1881) it certainly does not belong. 



1. M. centralis, n.sp. PI. VIII., fig. 3. 



Zocecia broad, hexagonal, with narrow, finely granular raised margins ; surface 

 slightly convex, silvery and very finely granular, with interspersed small, scattered, 

 usually bordered pores ; thyrostome in the upper third but at a considerable distance 

 from the anterior extremity of the zooeciurn, large, arched above, straight below, 

 slightly contracted towards the base and forming rather more than a semicircle ; 

 peristome thickened and raised. 



M.C. 



A beautiful and distinct species. 



2. 31. clarkei, Tenison Woods, sp. PL VIII., figs. 5, 6. 



Eschara clarkei, Tenison Woods, T.H.S.N.S.W., 1876, p. 2 ; Monoporella 

 sexangularis, Waters, Q.J.G.S., 1883, p. 43; id. 1885, p. 291. 



Zoarium large, flat, bilaminate and lobed, or foliaceous, with large, distant 

 fenestra. Zooecia hexagonal, distinct, with much-raised margins, the surface 

 depressed and hollowed but rising to the thyrostome, finely granular ; thyrostome 

 large, raised, arched above, straight or slightly hollowed below, situated close to the 

 upper extremity of the zooeciurn, with a thick, raised peristome. 



M.C. ; B.R. ; W.P. ; M. ; Batesford. 



Waters refers this to the Eschara sexangularis of Goldfress and Hagenow, and 

 he may be right ; but as there is some doubt I have retained Tenison Woods' specific 

 name, the species indicated by him being clearly identical with that here described. 

 The size of the thyrostome varies somewhat. Waters has found zooecial avicularia 

 in an Aldinga specimen. They must, however, be very rare, as they do not occur in 

 any of the numerous specimens I have examined. 



Family Cribrilinid.e. 



Zoarium encrusting or erect. Zooecia contiguous or disjunct ; front wall 

 formed by a series of ribs, constituted by modified marginal spines converging to a 

 median line, the intervening fissures remaining open, or forming grooves, or closed 

 at intervals by calcareous cross-bars so as to form perforated furrows. 



The essential character of this very natural family is that the front wall is 

 formed by the development and overarching of series of marginal spines which meet 

 and coalesce in the centre. The fissures between the ribs so formed may remain 



