Brooks and Ri^tenhouse.— On Turritopsis. 
PLATE 35. 
The convertion of the planula into a hydrorhiza; and the origin of the first 
hydranth as a bud. 
Fig. 
50. 
Fig. 
51. 
Fig. 
52. 
Fig. 
53. 
Fig. 
54. 
Fig. 
55. 
A section of a fully grown planula, with both ectoderm and endo- 
derm well defined. 
The planula has become a hydrorhiza, and the bud that is to be¬ 
come the first hydranth shows traces of the first cycle of tenta¬ 
cles. 
The tentacles of the first cycle are well developed. 
The rudiments of the tentacles of the second cycle are present as 
buds. 
Two cycles of well developed tentacles are present. 
All three cycles of tentacles are present. 
