226 THE AUSTRALIAN HYDROMEDUS^, 



8. FAMILY DICORYNID^E. Allman. 

 Generative Zooids free swimming Polypes with two tentacles 

 and without a mouth, carrying two ova each. 



These Zooids bud only on Polypostyles, and never on the 

 Alimentary Zooids which have one verticil of filiforine tentacles. 



SCHEMA. 



Ovum 



Free Polypoid 



I 

 Polyp Poly-postyl 



Hydrorldza 



I 

 First Polyp 



I 

 Ovum. 



Dicoryne. Allman. 



II. SUBORDER HYDROMEDUSIN^E. Von 



Lendenfeld, 1884. 



COLONIES OF POLYMORPHIC ZOOIDS. THE ALIMENTARY 

 ZOOIDS RETAIN THE SHAPE OF POLYPES, WHILST THOSE IN 

 WHICH THE SEXUAL PRODUCTS REACH MATURITY ARE 

 MEDUSAE, WHICH MAY BECOME FREE OR REMAIN ATTACHED 

 TO THE COLONY AND BECOME RUDIMENTARY. 



9. FAMILY ANTHOMEDUSIDA^E. Von Lendenfeld, 1884. 



Anthornedusa?. Haeckel, without the Cytaeidae of Haeckel. 



Medusae become free, without Otoliths, with Ocelli at the base 

 of the tentacles. Gonads in the outer or oral wall of the gastral 

 cavity. Mostly four Radial Canals. The Polype colonies on which 

 these Medusae bud, contain alimentary Zooids, which are not 

 invested by chitinous cups. The Medusae bud mostly on the 

 ordinary alimentary Polypes, exceptionally they are also born on 

 peduncles and bud direct from the Hydrorhiza. A division of 

 labour between alimentary Polypes and Polypes, which produce 

 Medusae, Polypostyles does not occur. 



