11 



together in modern systems of zoophytology under the 

 name of Hydrozoa*' or Anthozoa Hydroideaf. 



These also must propagate by ova, in order that the spe- 

 cies may be dispersed. In some species the germ-cells are 

 metamorphosed into ova at particular parts, and the con- 

 comitant growth of the soft tissue and outer crust furnishes 

 those ova with a capsule (PL I. fig. 2,/) ; which modifica- 

 tion in the growth of the coralline Prof. E. Forbes compares 

 with that " metamorphosis in flowering plants in which the 

 floral bud is constituted through the contraction of the 

 axis and the whorling of the individuals borne on that 

 axis, and by their transformation into the several parts of 

 the flower." 



The ova may escape from the ovi-capsule in the condition 

 of ciliated locomotive bodies, called ' planulae 9 by Sir John 

 Graham Dalyell ; or the planulae may be hatched in the 

 interior of a polype-individual developed from the summit 

 of the ovi-capsule, and which, after liberating them, may 

 wither and fall like the flower of a plant, as in some Cam- 

 panulariae%. Or a generative individual of a particular 

 form may be developed and become detached, and, by its 

 own power of locomotion, carry the contained ova to a 

 distance from the composite and fixed group of nutritive 

 individuals. 



The ova may be developed within the bell-shaped Aca- 

 lephoid prior to its detachment, as in the Coryne vulgaris, 

 observed by Wagner ||, or not until it has become de- 



* Owen, Lectures on the Corap. Anat. and Physiology of the Inver- 

 tebrata, p. 82, 8vo, 1843. 



f Johnston, History of British Zoophytes, p. 5, 8vo, 1846. 



I Lister, Phil. Trans. 1834, p. 375, pi. 10. fig. 1, 5, 6. (See PI. I. 

 fig. 2, g, t.) 



E. g. the Medusa octocilia and duodocilia of Dalyell, from Euden- 

 drium ramosum ; and the Tintinnabulum or Bell-medusa (PI. I. fig. 2, 

 observed by the same author to be developed from the Campanularia 

 dichotoma. Edinb. New Philosophical Journal, vol. xxi. 1836, p. 91. 



|| Isis, 1833, p. 256, t. xi. 



