Zoology.'] NATURAL HISTORY OF VICTORIA. \_Polyzoa. 



Plate 177, Figs. 4 and 5. 



CRASPEDOZOUM ROBORATUM (Hincks, sp.). 



Description. — Zoarium bilaminate, divided into flat, broadly-ligulate lobes. 

 Zooecia quadrate ; aperture occupying' greater part of the front, the sides and base 

 part!}' filled in by a sloping, thickened, granular lamina; a single erect spine on 

 each side above. On each side at the base of the zooecia, except the marginal, a 

 sessile avicularium on a rounded elevation, with the mandible directed obliquely 

 outwards ; the marginal cells with only a single avicularium. Ooecia somewhat 

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



References. — Membranipora rohorata, Hincks, Ann. and Mag. Nat. Hist., 

 Aug. 1881; Flustra menihraniporides, Busk, " CfiaUenger" Polyzoa, pt. i, p. 54, 

 pi. xxxii., fig. 7. 



Port Phillip Heads. 



These three forms constitute a well marked group, for which 

 1 have proposed the name Cras2}edozoum. It is allied to Flustra 

 and Membra^iijMra, or more projDerly to Biflustra, in the structure 

 of the zooecia, and to the first named in the lobulate and erect 

 habit of growth. 



C. roboratum and C. Ugulatum are much allied, and farther 

 observation may show that they ought to be ranked as varieties of 

 one species. In C. Ugulatum the lobes, besides being unilaminate 

 are much narrower, the zooecia are narrower, and there is usually 

 only a single avicularium at the base of each, while in C. roboratum 

 the lobes are broader, with about double the series of zooecia, and 

 there are two avicularia on the zooecia, except in the marginal 

 where there is only one. C. spicatum is quite distinct ; the zooecia 

 are not so calcareous, there is a larger filling in of the aperture, there 

 is a single, frequently lateral aviculai'ium similar to that of Cauda, 

 a second larger spine at the outer angle of the marginal zooecia, 

 and the posterior aspect of the zooecia is of an entirely different 

 shape. The ooecia also differ markedly in being produced upwards 

 into a sharp apiculate point or spike, and the anterior depressed 

 area is very small. 



Explanation of Figures. 

 Plate 177. — Fig. 4, portion of specimen, natural size. Fig. 5, another specimen, natural 

 size. Fig. 6a, portion of same, magnified. 



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