Zoologtj.\ NATURAL HISTOKY OF VICTORIA. \_Polyzoa. 



Plate 96, Figs. 1-6. 



EETEPORA PORCELLANA (P. McG.). 



Description. — Polyzoaiy massive, expanded, convoluted, or calyculate _; 

 fenestrce elongated; cells rliomboidal, separated by distinct raised lines, terminating' 

 superiorly o])posite the lower part of" the mouth ; mouth arched above, straight or 

 slightly hollowed below; lower lip entire, with (usually) an avicularium below it; 

 a spine articulated on each side ; operculum rounded, wider than high ; an elliptical 

 avicularium on the front of the cell, with a spatulate or linguiform mandible directed 

 vertically or obliquely downwards ; ovicell rounded, smooth, or with a few ridges, 

 much immersed, when young with a broad, short, vertical opening, which, as growth 

 advances, becomes filled in, and in some cases forms a slightly prominent ridge ; 

 dorsal surface obscurely granular or slightly areolated, traversed by numerous raised 

 lines, and usually with one or more small oval avicularia on each part defined by 

 those vibices. 



References.— P. H. MacGillivray, Tr. Roy. Soc. Vict., 1869 and 1882; 

 R. robusta, Hincks, Ann. and Mag. Nat. Hist., May 1878. 



Port Phillip Heads. 



Varies a good deal in appearance, according to age, old speci- 

 mens being very massive, the fenestra? shorter and interspaces 

 thicker than in yonnger individuals. The form of the lower lip 

 varies. It is usually straight and entire, with a rounded avicu- 

 larium immediately below. Sometimes there is a slight fissure in 

 place of the avicularium, and occasionally there is a fissure towards 

 one side, and on the wider part of the lip an avicularium. In young 

 marginal cells there is no appearance of any sinus. Frequently 

 the central part of the cell is depressed. A variety occurs which 

 I have named laxa., presenting so marked a difference in its appear- 

 ance that I was inclined to consider it as a distinct species. In it 

 the fenestrse are very long, and are formed by the irregular division 

 and anastomosis of l)road l)ranclies from a main stem. The cells 

 are usually longer, the separating raised margins not so prominent, 

 and many of the oral spines, of which in the marginal cells there 

 are frequently four or five, are very long and jointed, as in R. 

 monilifera^ but much more slender. An old dead specmien of this 



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