124 Selections. [No. 7, new seeies. 



We cannot hope for a well grounded classification of the Me- 

 dusas until the connection between them and the Polypi is pro- 

 perly established ; many different forms abound , in all seas, but 

 can now only be classed according to the normal number and ar- 

 rangement of their organs. 



The family «of the " Mushroom-medusas" (Medusidce) has a 

 roundish umbrella-shaped covering, with a four-sided mouth in 

 the middle, which is surrounded by four seizing arms : indeed all 

 the organs are arranged according to the number 4 ; the bodies on 

 the edge, of which there are at least 8 of a brilliant red, and 

 in young individuals are so clearly jagged outwards that they ap- 

 pear as if lying on cone-like extensions. To this family belong 

 the " Ear-medusas" (Aurelia) the " Sea-lamps" (Pelagia) see plate 

 iv. fig. 1 , and many other widely spread genera. Medusa, Cyanea, 

 Ephyra, Chrysaora. 



Very nearly related to this is the family of the " Sea-medusas" 

 (Oceajiidce) the organs of which are also arranged according to the 

 number 4. The body is bill or hat-shaped ; the mouth simple, 

 and placed at the end of a long probosics ; the threads attached to 

 the disc are branched in some genera, in others simple. To this 

 family belong nearly all those Medusas which have been consider- 

 ed as direct descendants of the " Tube-polyps" [Tjjhidaridce) and 

 have been called Cladonema, Sthenyo, Callichora, Sfc, Oceania, 

 Thaumantias, Cytacis, Callirhoe. 



The family of the " Disc-medusas" (Aequoridce) has a flat lentil- 

 shaped disc, with colourless bodies on the edge, and generally 

 very short threads. The number 6 seems to reign amongst them ; 

 the mouth is uncommonly large and not surrounded by any seiz- 

 ing-arms. Aequorea, Cwiina, Eurybia, Aegina. 



The " Hair-medusas" (Berenicidce) have a flat bill with innu- 

 merable extremely fine hairs at the edge, > through which very thin 

 canals seem to rise upwards. In the disc itself only one vessel 

 can be seen, resembling a branching cross, so that the number 4 

 seems to rule here. Apparently the nourishment is sucked in by 

 means of the threads at the edge ; at least no digestive organs 

 have hitherto been discovered. 



