118 EXPLANATION OE 



for a time. Figs. 1, 2, 3 are viewed from the wider 

 end, and fig. 4 from the narrower. At the wider 

 end is seen a depression, by which they afterwards 

 affix themselves by suction. 



Fig. 5. An individual wliich has already afiixed itself at 

 the surface of the water. 



Figs. 6-9. Show the way in which the young Medusce 

 after (on the third day) having become attached by 

 the wider end to some fixed object, gradually grow 

 and change their form, imtil the hitherto slender, 

 projecting extremity becomes thicker, and the body 

 passes through the cyhndrical (figs. 7, 8) into the 

 clavate form (fig. 9.) 



Fig. 10. A club-shaped individual, seen from above, in 

 which now an actual opening (but no oral orifice) 

 has been formed ; this orifice is surrounded by a 

 circular elevated margin, and presents four indis- 

 tinct tubercles. 



Figs. 11-14 represent a similar individual in its ad- 

 vancing growth ; the four inferior tubercles are 

 gradually more and more elevated (on the fourth 

 and fifth day) (figs. 11, 12, 13) finally become 

 filamentous and assume the form of tentacula 

 (fig. 14.) 



Figs. 15, 16. Individuals at the age of from ten to 

 eleven days ; the number of tentacles is increased 

 to eight, four new ones having sprung up between 

 the older ones ; fig. 15 is seen from the side, fig. 16 

 from above. 



Fig. 17. An individual which besides the eight older ten- 

 tacles, exhibits five new ones springing up : viewed 

 from above (on the twelfth day.) 



