SCYPHOMEDUS> OF THE AUSTRALIAN SEAS. 23 



III. Sub-orclo RHIZOST03LE. 



Cuvier. 



Diseomedusa? with eight large root-shaped simple or branched mouth-arms 

 in the tertiary i-adii, with numerous suction-mouths on, or a deep furrow in, 

 each mouth-arm, without tentacles. 



Familia CHAMIOSTOMID.E. 



Von Lendenfeld, 1882. 



Rhizostoma? with a continuous sub-genital porticus. The mouth-arms which 

 originate from the brachial disc are pinnately branched, and possess on the 

 ventral side a deep groove, bridged over in one locality only to form a filament, 

 by the local coalescing of the membranous lateral extensions. Scattered 

 serata throughout the gastro-vascular system. 



Genus PSEUDORHIZA. Von Lendenfeld, 1882. 



With one large filament at the bifurcation of one or all eight arms. The 

 canal system consists of 16 radial canals and a ring canal. Centrifugally from 

 the ring canal we find an anastamosing network of canals, whilst centrifugally 

 there are between two adjacent main radial canals, ten canals running from the 

 ring canal inwards radially. 



PSEUDORHIZA AUROSA. R. von Lendenfeld. 



Pseudorhiza aurosa, R. v. Lendenfeld. Zoologischer Anzeiger, Nr. 116 ; 

 band v, Seite 380. 



Pseudorhiza aurosa, R. v. Lendenfeld. The Scyphomedusa 1 of the Southern 

 Hemisphere. Proceeding of the Linnean Society of New South Wales ; 

 Volume ix, part 2, page 293. 



Umbrella three or four times as broad as high, with a reticulate figure on 

 the dorsal side. In every octant between the two long and narrow ocular 

 flaps there are six velar flaps, each of which consists of three secoiidary flaps. 

 Arms about as long as the diameter of the umbrella. 



Colour. Umbrella colourless, with a violet reticulate figure covering the 

 ex-umbrella. Entoderm of gastral cavity, brown ; upper part of mouth-arm- 

 grooves, rose coloured ; arm, colourless and transparent ; frills along the 

 margin of the grooves, and distal end of long filament, richly violet. 



Size. Diameter of umbrella, 400 mm. ; thickness of gallert of umbrella, 

 30 mm. ; brachial disc, 220 mm. in diameter, and 25 mm. in thickness. 



Ontogenesis. The embryos are carried about in pouches suspended in great 

 number from the radial canals, which run centripetally from the ring canal. 



