140 Australian Polyzoa. 



from the circumference to the base ; these compartments 

 vary at their widest parts from one to three inches. The 

 flexible stem is two inches high, an inch and a-half in 

 diameter immediately above the root, and almost an inch at 

 its junction with the rigid polyzoary ; it is rough and 

 irregularly transversely annulated. There are no ridges or 

 prolongations of the stem on any part of the polyzoary. 



Genus RETEPORA, Imperato. 

 R. porcellana. 



Polyzoary expanded, waved or convoluted, thick ; fenes- 

 tras elongated, about as wide as the subcylindrical 

 interspaces. Cells oval or rhomboidal, smooth. An avicu- 

 larium towards the middle of a cell, mandible short, 

 generally directed vertically or nearly so, sometimes 

 obliquely ; occasionally there is also an avicularium placed 

 obliquely on or below the lower lip. Dorsal surface vibicate. 



This is distinguished from all the other Victorian species 

 which I have seen by the size of the fenestras which are as 

 wide as the interspaces, and by the interspaces being thick 

 and subcylindrical. 



R. granulata. 



Polyzoary thick, expanded, foliaceous, convoluted ; fenes- 

 tras small, short, oval, not so wide as the interspaces. Cells 

 ovate, whole surface granular. Ovicell immersed, granular. 

 Dorsal surface faintly vibicate. 



This species may at once be distinguished from the last 

 by the different form and size of the fenestras, which are 

 much smaller and rounded. The whole surface is finely 

 granular, and the granulations give to the edges of the 

 fenestras a crenulated appearance. 



R. fissa. 



Polyzoary expanded, foliaceous ; fenestras round or slightly 

 elongated, about the same width as the interspaces. Cells 

 ovate, separated by narrow raised lines, with an avicularium 

 towards the centre, the mandible directed downwards and 

 outwards. Ovicell globular, smooth, with a slit in front. 

 Dorsal surface vibicate. 



In this species the polyzoary is much thinner than in -the 

 other two here described, and the fenestras which are small 

 are of about the same width as the interspaces. From R. 

 monilifera it is at once distinguished by the difference in 

 the ovicell. 



