36 DISCOPHOR^. Part III. 



The Ephyra^ of Aurelia flavidula. By the time the young medusa has com- 

 pleted its strobila stage of existence, the different regions of the body are sufficiently 

 developed to be easily identified Avith similar parts of the adult; and we will 

 therefore now give them their j^rojjer names, before proceeding to describe the 

 ephyra in a free state. The eight lobes (PI. XL Fig. 29 j) are the oculiferous 

 lobes (see PI. VI. Figs. 1 and 4), and the lobule (PI. XL Fig. 24 h) is the ocular 

 peduncle (PI. Yl. Fig. 4 o). The intervals (PI. XL Figs. 6 and 17 r) between the 

 lobes become the tentaculiferous edge (PI. VI. Fig. 2, h; PI. VII. Fig. 3 b), and the 

 broad papilla (PL XL Fig. 24 /) in each of these intervals the marginal veil (PI. 

 VIL Fig. 2 c ; PL VIIL Fig. 5 c). The digitate bodies (PL XL Fig. 24 g, Fig. 26 e) 

 are the genital appendages (PL VIIL Figs. 7 and % c; PL IX. Figs. 1 and 2 c). 



When the young Aiurelia has parted from its attachment, it assumes a position 

 reverse to that which it held in the strobila state, and swims Avith its proboscis 

 hanging downward (PI. XP. Figs. 21, 23, 24, 27, and 28). It is true that the strobila 

 is capable of living in any 2:)Ositiou, either attached to stones, logs, etc., and standing 

 up so that the mouths of the ephyrse are upward; or the base of the strobila 

 may be uppermost, when it is attached to the under-side of floating bodies, such 

 as sea-weeds, floating timbers, and the like, and in this condition the ephyra^ hang 

 with the proboscis downward, just as they do when swimming individually. That 

 there is an essential reversal of position when the ephyra) become free is, therefore, 

 only seeming ; for, although it is true that the meduste do not naturally rest with 

 the mouth upward, yet they swim in this position very often. The proper time 

 to ascertain the shape of the young ephyra is when it is in a state of rest, and 

 then we see that it reseilibles an umbrella, or, perhaps, more closely, that kind of 

 parasol which has a hning to cover the wires on the under-side, or even a common 

 mushroom, inasmuch as that ' has a thick pedestal : in reality, the geometrical 

 expression for it would be, double convex. When swimmmg it assumes a variety 

 of shapes, all of which, however, are the result of the upward and downward 

 motion of the periphery of the disk : at one time we may see the umbrella 

 reversed {Figs. 21, 24, 27, and 28), so that it resembles a common fruit dish on 

 a pedestal; or, when this position is changed by the vigorous downward stroke 

 of the periphery and the animal shoots forward, the extreme of the ojjjjosite shape 

 is assumed, and the body resembles a mushroom with its periphery curved down- 

 ward and inward, just before its edge breaks loose from the stalk at the moment 

 of expansion {Fig. 23). Oftentimes the little medusa may be seen floating with 

 its body slightly depressed above, and its oculiferous lobes stretched outward to 

 the utmost {Figs. 24 and 28), as if to offer the greatest amount of surface to the 



^ See Vol. III. p. 80 for the meaning of the tvord Ephyra as used here. 



