12 DESCRIPTIVE CATALOGUE OF THE 



in the most differentiated genera. In others no such sub-gastral portions is 

 found, but only four deep depressions (Schirmhahlen), dividing likewise the 

 parochial disc from the umbrella. To the vestibule stomach eight large mouth- 

 arms are appended, which are situated in the tertiary radii. These possess a 

 deep groove leading to the vestibule stomach in the Chamoostomidse. 

 (Pseudorhiza, V. Lendenfeld.) In the true Rhizostomous niedusse the two 

 sides of the groove form extensive folds, and coalesce in many places, so that 

 numerous irregular and small apertures are formed instead of the simple one 

 in other medusae. 



The mouth-arms are always, in whatever way they may be developed, 

 clothed with entoderm on the inner, and with ectoderm on the outer side. In 

 the margin the cuidoblasts are particularly numerous, and here also sensitive 

 cells are found. The sub-epithelial layers contain muscular fibres, which 

 extend in eveiy direction, and enable the medusa to move its mouth-arms. 



The Scyphomedusse are present in all seas. The largest species (species of 

 Cyanea) are found in the temperate zone. 



Their geographical distribution depends to a great extent on the oceanic 

 currents, but too little is known of the Australian species at present to allow 

 of any conclusions regarding the distribution of the Australian species, to be 

 described below. 



THE AUSTRALIAN SPECIES. 



In the following pages all Australian species hitherto discovered are 

 described with full references. The classification is that of Haeckel, amended 

 according to the results of the recent investigations of Glaus and myself. 



