AND THE LOWER ANIMALS. 1~jO 



Although, still imperfect, yet when they reach this 

 condition of development, the divisions of the strobila 

 show unequivocal signs of individualization. Each 

 of them moves its own fringed border separately, 

 and if a single one be touched, it alone will contract. 

 In order that all these divisions of the former animal 

 may become as many distinct individuals, it is neces- 

 sary that they separate; and this they speedily do. 

 The topmost one, that which bears the tentacles 

 of the scyphistoma, is first detached, and those which 

 succeed it are similarly removed, and swim away 

 through the water after the manner of acalephs. 

 They are now medusoids, but not yet aurelias, and 

 Saars very fairly compared them to the species of 

 another genus — the eight-rayed ephyra (Ephyra 

 octoradiata) . 



Neither the form nor the organization is what it 

 will be eventually, but the larvae are soon fully de- 

 veloped. At first flat, as above described, they now 

 become more and more convex on one side and 

 concave on the other; the gastro- vascular canals 

 make their appearance ; the mouth is opened and 

 surrounded by its tentacles ; the marginal cirrhi 

 present themselves, at first few in number, but after- 

 ward more numerous, and the reproductive organs, 

 male and female, are formed in separate individuals, 

 and soon commence the performance of their functions. 

 Finally, instead of a solitary infusorian, or of a more 

 or less branched scyphistoma, or of a strobila more 

 or less segmented, or; even of a swarm of Epliyras, 

 we perceive numbers of red aurelias, exactly like that 

 which laid the primitive ovum, but was unable to 

 reproduce itself directly. 



