BY R. VON LEN T DENFELD, PH.D. 921 



species. The Umbrella is flat, and always reversed. I have 

 examined hundreds of these Obelias lately, and have always found 

 the Umbrella in this apparently abnormal state. But as these 

 Obelias seemed perfectly healthy, and were obtained together 

 with other Medusa? which never reverted the Umbrella, I am led 

 to suppose that this is their natural position. All Obelias seem to 

 have the extraordinary habit of reverting the Umbrella, and even 

 of fastening themselves to foreign bodies by means of the mouth. 



Whilst the other Australian species, O. geniculata, is often 

 found with non-reverted Umbrella, and also the young larvse of 

 O. Australis present that appearance, I have never seen an adult 

 Medusa of this species in another position from that represented 

 in the figure. (Fig. 19.) 



The Gonads are situated in the distal part of the Radial Canals, 

 oval and thicker at the distal than near the proximal end. The 

 Radial Canal widens at the proximal end continuously into the 

 cavity of the Gonad. In the distal end the Radial Canal enters 

 and widens abruptly into the fundus of the cavity. (Fig. 21.) 



The male genital products are produced by a continual division 

 and subdivision of the cells in the Subumbral wall of the Gonad. 

 A thin layer of Ectodermal Epithelium covers the Gonad. It 

 appears as if the Spermamother cells were Entodermal. The 

 division of the cells goes on more rapidly towards the cavity, so 

 that these cells always appear smaller (tig. 21e) than the outer 

 ones (g). From the inner surface lines extend centrifugally (fig 

 27f), and it appears that these lines are minute channels in 

 connection with the Gastral cavity, through which nourishing 

 material flows to the growing Spermatozoa. 



The stomach (fig. 19) is spherical, and we find attached to it a 

 short Manubrium, with four short, cylindrical Moutharms in the 

 Perradii. Looked at from above the stomach appears quad- 

 rangular. (Fig. 20.) 



