112 DISCOPHOR^. Part III. 



lobes of Aurelia, as represented in PI. XP. Figs. 19, 25, 26, and 28, h h, and PI. XP. 

 Figs. 4 and 17; and the resemblance is greater, in projDortion as they are younger. 

 The eye is truly a tentacle-like prolongation of its radiating pouch (PI. IV. Fig. 

 1, 0, and PI. V''. Fig. 8, o),' which is alike in the adult and the young, except 

 that in the yoinig the peduncle of the eye is flanked by two simple lapj^ets, as 

 in the young Aurelia, while in the adult the lappets have become complicated 

 lobes, with ramified channels, branching from the main 230uch, with two horns 

 toward the margin. The lappets of the oculiferous lobe of the young, with the 

 intervening eye upon its peduncle, have, in reality, become the complicated termi- 

 nation of the ambulacral pouches and of the main ovarian pouch (PI. IV. Fig. 

 1, o" o"), their medial emargination corresponding to the space intervening 

 between the two lappets in the young, at the base of which projects the eye, 

 with its peduncle, as seen PI. IV. Fig. 3, a b c. The lappets themselves have 

 become hollow lobes, as is seen to particuhar advantage in PI. V\ Fig. 24, o', and 

 Fig. 23, 0, the main cavity of each lappet sends off dendroid ramifications to 

 the margins of the lobes. In proportion as the Cyanea grows older, these rami- 

 fications become more and more complicated, and extend even upon the sides of 

 the slit separating the two lappets, as seen in PL V". Fig. 23, o, and Fig. 7, o, in 

 which c indicates the eye, with its joeduncle. The same is highly magnified in 

 Fig. 8, in which o marks the main cavity of the ocular chamber, and o the eye 

 itself Like a tentacle, this organ is capable of a certain extension and contraction ; 

 in Fig. 8, PI. V''., it is represented in its utmost state of contraction, in Fig. 3, 

 PI. IV., it is shoAvn in its utmost state of elongation, as seen from below. 



S E € T I O N V 



HISTOLOGY OF CYANEA. 



Little has Ijeen done, thus far, towards an histological investigation of Cyanea, 

 and a thorough survey of all its parts would, no doubt, lead to interesting results, 

 judging from those which have alread}' been examined. The curtain of the acti- 

 nostome especially presents interesting jaoints^ the folds of the flowing curtains, 

 when elongating and shortening, present, alternately, prominent longitudinal and 

 transverse lines, which are undoubtedly the result of the change of their tissue ; 

 for when inactive they are smooth. The longitudinal lines between the folds are 

 particularly distinct in the state of utmost relaxation, when the elongated cells, 

 hanging in bundles, in a vertical direction, between the folds, are most clearly visible. 



