﻿Dec, 1856.] 



ELLIOTT SOCIETY. 



77 



sion is now at hand, the proboscis loses its inordinate length, the 

 digestive cavity has assumed distinctly the eight-pointed form rep- 

 resented PL 7, fig. 32, and the larva quits its hold of the parent's 

 body, and is driven out the next time the bell is emptied of its 

 watery contents. 



Immediately after expulsion, I have observed the discophorous 

 larva to remain still for a short time, allowing itself to sink, and 

 seeming to wait for some necessary stimulus to the exertion of its 

 new powers of pulsatile motion. Then begin a few wavering 

 strokes, as if it were just trying its wings, and a short time after 

 the young animal may be swimming about like any other Medusa, 

 with its proboscis hanging down like that of a Tima or Geryona as 

 exhibited in fig. 31, PL 7. 



If, now, we carefully consider fig. 31 and 32, PL 7, of which one 

 is a profile view of the larva at this stage, and the other a view 

 from above, we see, that it is no longer a hydra, but a veritable, 

 though imperfect, Medusa, in which the radiating tubes are not 

 yet formed. The veil by this time is so highly developed as to 

 be entirely unmistakable, forming a delicate membranous ring 

 beneath the scalloped margin of the watchglass-shaped disk to 

 whose thickened cordlike border it is attached, following the mar- 

 gins of the lobes, and so projecting in their interspaces up to the 

 very base of the eight tentacula. This is, of course,, the position of 

 the vail in all the Naked-eyed Medusae, and the thickened b.order 

 of the disk, is also conspicuous in Thaumantias and the allied 

 Genera, the only difference being, that there it follows a straight 

 course round the straight margin, while here, the margin being 

 lobed, the attachment of the vail must, of course, follow its sinu- 

 osities. In both cases the tentacula are in immediate connection 

 with this cord and the vail, and in both cases the otolithic vesicles 

 here attached just to the nether edge of the chord have the same 

 relative position. A comparison with the otolithic vesicles round 

 the margin of the young habitually reversed Campanularian Me- 

 dusa will give the same result. Just above each of the otolithic 

 vesicles, and apparently in connection with the marginal cord is a 

 conspicuous prominence, of a somewhat different cellular structure 

 from the surrounding parts. This may be a rudimentary tentacu- 

 lum, and at least it strongly reminds us of the similar prominences 

 in Thaumantias, and also of that described by Milne Edvv. in 

 iEquorea, save that here there is no indication whatever of a mar- 

 ginal tube, and consequently no connection between this knob and 



