CNIDARIA 



103 



by means of its anterior end. The further development could not be 

 followed. K. S. Bergh, however, mentions a young stage in which the 

 tentacles were not yet united into groups, but were distributed along the 

 margin of the bell, while the arms were not yet developed. Eight ten- 

 tacles lying in definite radii could be recognized as fundaments of 

 marginal papillae. 



Charybdeidae. — W. Haacke (No. 106) has given a description of some 

 young forms of the Australian CharybdEea Rastonii, which already con- 

 siderably resembled the adult animal. These accounts are thus far the 

 only ones on the embryology of this genus. As contrasted with the 

 cubical form of the adult animal, the young Acalephs showed an 

 approach to a pyramidal shape, and the apex of the umbrella was more 

 strongly arched than in the adult. The youngest stage that was observed 

 exhibited a canal somewhat excentrically situated, and extending from 



KiG. 49.— Three stages in the develop- 

 ment of Lucernaria (after R. S. Bbrgh), 



Fig. 50.— Non-sexual reproduction 

 of the Scyphistoma (after M. Sa.eS) 

 —A, by the formation of stolons; B, 

 by lateral budding. 



the central stomach to the dome of the umbrella, where it ended blindly. 

 Haacke regards it as the remains of a communication with a Scyphis- 

 toma nurse, and therefore maintains the probability of an alternation of 

 generations in the Charybdeidae. 



From the egg of most Discophora (Discomedusoe) a fixed 

 polypoid creatare is first developed, which is attached bj 

 one pole, and has the mouth at the opposite end, at some 

 distance from which a circle of tentacles is developed (Fig. 

 51, 3, 4). The Lncernaridae are essentially a more highly 

 developed form of these scyphopolyps, which become sexually 

 mature. In all other Scyphomedusae the polypoid form 



