DISCOPHORiE. 



37 



time (Fig. 43). A little later the lobes enlarge, the movements 

 become more lazy ; it assumes both in form and habits the char- 

 acter of the adult Bolina. 



The series of changes through which the Ctenophorae pass 



Fig. 41. Fig. 42. Fig. 43. 



are as remarkable as any we shall have occasion to describe, 

 though not accompanied Avith such absolutely different con- 

 ditions of existence. The comparison of the earlier stages of 

 life in these animals with their adult condition is important, 

 not only with reference to their mode of development, but also 

 because it gives us some insight into the relative standing of the 

 different groups, since it shows us that certam features, perma- 

 nent in the lower groups, are transient in the higher ones. A 

 striking instance of this occurs in the fact mentioned above, that 

 though the long tentacles so characteristic of the adult Pleuro- 

 brachia exist in the young Bolina, they yield in importance at 

 a later period to the lobes which eventually become the pre- 

 dominant and characteristic feature of the latter. 



DISCOPHORiE. 



The disk of the Discophorae is by no means so delicate as that 

 of the other Jelly-fishes. It seems indeed quite solid, and some- 

 what like cartilage to the touch, and yet so large a part of its 

 bulk consists of water, that a. Cyanea, weighing when alive about 

 thirty-four pounds, being left to dry in the sun for some days, was 



Fig. 41. Young Bolina in stage resembling Pleurobrachia ; greatly magnificil. 



Fig. 42. Young Bolina seen from the broad side, with rudimentary auricles and lobes; magnified. 



Fig. 43. The same as Fig. 42, seen from the narrow side. 



