PLATE XXI. 



Fig. 1. The end of a branch of Halecium muricatum, which has 

 fastened itself on a shell and has formed stolons, x 12. 



— 2. Halecium labrosum. From a hydrotheca grows, instead of a 



new hydrotheca, a long, wrinkled thread which has fastened 

 itself to a shell and formed stolons, x 12. 



— 3. A hydrotheca of Halecium labrosum with an unusually long 



pedicel, x 50. 



— 4. A piece of a colony with three hydranths of Halecium curvi- 



caule. X 18. 



— 5. A piece of a colony of Halecium textum n. sp. x 18. 



— 6. Two hydrothecae (a pseudohydrocaulus) of the same species, 



showing a. o. the pseudodiaphragm. x 75. 



