EXPLANATION OF THE FIGURES. 



PLATE I. 



Figs. 1-40. The development of Medusa Aurita. 



N.B. Almost all the figures are taken from the 

 memoh" by Sars, in Erichson's Arch., 1 B. 1 H. 

 tab. i — ^iv, some from a work by the same author, 

 entitled ' Beshivelser og lagttagelser over nogle 

 mcerkelige eller nye i Havet ved den Bergenske Kyst 

 levende Dgr, o. s. v.' {Bergen, 1835.) Eigs. 1 — 19 

 represent especially the progeny of Cyanea capillata, 

 but according to Sars it corresponds so perfectly 

 with that of Medusa aurita, that in most cases it is 

 impossible to distinguish the one from the other. 

 Fig. 35-40 only are from my original drawings, 

 made in my Icelandic journey. 



Figs. 1-19. Slioio the development of the first genera- 

 tion, which I have named Medusa-nurses. 



Figs, 1-4. The ciliated, free-swimming, infusorial 

 progeny of the Medusce, newly escaped from the 

 peculiar receptacles in the tentacles of the female 

 Medusa, in which they undergo a sort of incubation 



