32 A MONOGRAPH OF THE TERTIARY POLYZOA OF VICTORIA. 



Caj)e Otway, Mr. Dennant. 



I have only a single specimen of this very interesting form. The thyrostome 

 differs from that of the other species in its thin raised peristome. The ovarian pores 

 are very large, when fully formed occupying the whole of the upper part of the 

 zooecium hetween the peristome and the cell margins. The avicularia are somewhat 

 similar to those of the smaller C. gracilis. 



Family Plustrid^e. 



Zoarium expanded, flexible, memhrano- calcareous, erect, foliaceous, ligulate or 

 spirally twisted round an imaginary axis, uni- or bilaminate. Zocecia elongated, 

 separated by raised margins ; front entirely membranous, or partly filled in by a 

 thickened calcareous lamina. 



Craspedozoum, McG. 



Zoarium erect, in ligutate divisions, uni- or bilaminate, each branch bordered 

 throughout its whole extent by a bundle of radical fibres springing from the bases 

 of the lateral zooecia, Zooecia quadrate, aperture partly filled in by a thickened 

 lamina. Ooecia external. 



1. C. roboratum, Hincks, sp. PL IV., fig 5. 



Membranipora roborata, Hincks, A.M.N.H., Aug., 1881 ; Waters, Q.J.G.S., 

 1883, p. 433; Craspedozoum roboratum and ligulatum, McG., P.Z.V., 177; Flustra 

 membraniporides, Busk, C.P., Pt. I. ; p. 54. 



Zooecia largely open in front, the aperture partly filled in below by a narrow 

 granular lamina ; a spine at each upper angle ; one or two sessile auricularia on 

 rounded eminences below the aperture. In recent specimens the ocecia somewhat 

 mitriform, the upper rim thickened, and a depressed area inferiorly. 



M.C. ; W.P. (W.) Living. Australia and New Zealand. 



In P.Z.V., to which I refer for full descriptions and figures, I described three 

 species. Of these, however, C. roboratum and C. ligulatum differ chiefly in the 

 former being bilaminate, the latter being unilaminate and narrower. These 

 differences are scarcely of specific value, and I, therefore, now unite the two forms. 

 The fossils which I have seen are unilaminate. 



Hincks referred this species, but somewhat doubtfully, to Membranipora ; and 

 Waters (AM.N.H., Sept., 1887) agrees with him, uniting also all my three species 

 in one. C. spicatum, however, is totally distinct in essential specific characters. 



