56 A MONOGRAPH OF TIIK TERTIARY POLYZOA OP VICTORIA. 



ponnaiuMitly opon, or Ix-conic closed tlivou^hoiit llic wholo extent, theiv situation 

 being still marked by a snture or groove, or tbey may be closed at intervals by 

 calcareous cross-bars or Iraheculoc leaving regular scries of openings or pores. 



Membraniporella, Sniiff. 



Zoai-iiuu eiicriistiiig or foliaeeous. Zocccia contiguous or disjunct; closed in 

 front by a series of more or less consolidated calcareous ribs. 



1, 31. disfaiis, McG. 



Membraniporella distans, McG., P.Z.V., 187. 



Two single damaged zooecia from Muddy Creek belong either to M. distans or 

 the well-known closely allied European M. nil /da. The specimens are not sufficient, 

 especially in the absence of on?cia, for satisfactoiy identification, but as 3f. nitida 

 lias not, so far as I know, been found living in Australia, I refer them to the recent 

 A'ictorian species. 



2. M. tei/iiicos/a, n.sp. PI. VIII., fags. 15, 16. 



Zooecia ovate, distinct, se])arated by narroAV grooves ; outer part of anterior 

 surface" sinnotli. middle ])art raised and formed by a series of 8-10 narrow ribs on 

 each side eiulimi' in a narrow central ridge, the intervening fissures remaining open 

 or partly or wholly hlled in by a thin calcareous extension from the ribs ; thyrostomc 

 large, wider and slightly arched above, Iowcm- lip slightly hollowed and with a 

 prominent denticle on each side ; thyrostomc of ovicelligcrous cells Avide, nearly 

 semicircular, the lower lip straight or very slightly hollowed and without denticles. 

 Oa>cia large, prominent, rounded, a vertical raised rib with a de]n'(>ssion on each 

 side extending nearly the whole length. 



S.P.; M.C. 



The furrows between the ribs are in most of the zooecia filled in by a thin 

 calcareous membrane along the centre of wliich is a partial or complete slit-like 

 fissure which is fre(|uently closed, its situation being then usually indicated by a 

 faint line. This species differs from the others of the genus in the exceeding 

 narrowness of the ril)s and the more complete denticulate thyrostomc. Except for 

 tlie al)sence of the; trabecuhc between the I'ibs and their great tenuity, it bears a 

 considerable resem])lance to CrihriUna orhiculc. I am not quite satisfied that it 

 ought not to be referred to Cribrilina, as I have an imperfect s])ecimen, which 

 may belong to the same sjiecies, in which the margin, although narrower, is smooth, 

 the front a little broader, the ribs thicker and joined by regular small trabeeukc and 

 the thyrostomc of nearly the same structure but not so widened above. At the 



