METAZOA COELENTERA. 97 



either an animal or a rock, and should bud, then a colony 

 would arise. This is precisely the case with Cunocantha 

 ( Cunoctantha^} octonaria Hkl., or Cunina octonaria 

 McGrady, the latter name being the more familiar one. 

 PI. 113 gives the development of this genus, and No. 114 

 is the medusa of Cunina campanulata Ed. PI. 113, fig. i, 

 is the larva. (Figs, i and 3 are drawn in a position to 

 show the hydra-like larva; fig. 5, to show the medusa-like 

 adult.) The aboral end of the body is shortened; there 

 are two opposite tentacles which have clusters of thread 

 cells at their ends. The oral cone which extends above 

 is very long and at its end is the small mouth. The 

 internal cavity is lined with large endodermal cells seen 

 in the figure. The ectoderm is thin excepting at the 

 extremities of the tentacles and at the aboral end of the 

 body. This larva now enters the bell cavity of Turritop- 

 sis, another Hydrozoan, and fastens itself by its tentacles, 

 as seen in fig. 2. The oral cone becomes extremely long, 

 is inserted in the mouth of Turritopsis, and two more 

 tentacles grow. This stage is more clearly seen in fig. 3. 

 Either before or after the secondary tentacles appear, the 

 hydra puts forth buds from the aboral end of the body 

 and a colony is formed as seen in figs. 4 and 5. A rim 

 grows out from the body in the tentacular zone and this 

 rim becomes divided into eight lobes, each one of which 

 contains a branch from the central digestive cavity. The 

 bud, thus changed, escapes into the water and is a medusa 

 (PI. 1 13, fig. 6) with a long oral cone. Later the umbrella 

 enlarges while the oral cone remains about the same as 

 seen in fig. 7, which is an aboral view of an adult medusa. 

 Each member of the colony becomes converted into a 

 medusa, so that here we have budding and a primitive 

 kind of metamorphosis but no alternation of generations. 

 The Cunina parasitica, however, which attaches itself 



1 H. V. Wilson, Stud. Biol. Lab. Johns Hopkins Univ., IV, no. 

 2, 1887, p. 95. 



