118 AMEMOAN HYDKOIDS. 



Plate 21. 



Fig. 1. Obelia commismmlis McCrady. Living colony (enlarged). 



2. Obelia commissuralis. Living hydranth (enlarged). 



3. Obelia commissuralis. Gonangium (enlarged). 



4. Obelia coinmissuralis. Medusa, lateral view (enlarged). 



5. Obelia commissuralis. Medusa, dorsal view' (enlarged). 



Plate 22. 



Fig. 1. 06ei!ia swrcw/om Calkins. Branch, showing modified termination (enlarged). 



2. Obelia surcularis. Hydranth (enlarged). 



3. Obelia flabellata (Hincks). Branch (enlarged). 



4. Obelia flabellata. Medusa (enlarged). 



5. Obelia borealis Viwtting. Part of type colony (enlarged). 



6. 7. Obelia borealis. Gonangia (enlarged). 



Plate 23. 



Fig. 1. Obelia longissima (Psiilaa). Part of colony (enlarged). 



2. Obelia longissima. Part of another colony showing corrugated hydrothecse (enlarged). 



3. Obelia longissima. Hydrotheca (greatly enlarged). 



4. Obelia grijfmi GaX^hiB. End of branch (enlarged). 



5. Obelia griffini. Hydrotheca and gonangium (enlarged). 



6. Obeliafragilis Ciklkms. Part of branch (enlarged). 



Plate 24. 



Pig. 1. Obelariagelatinosa (Fallas). Branch (enlarged). 



2. Obelaria gelatinosa. Hydrotheca (greatly enlarged). 



3. Obelia gelatinosa. (" Obelia castellata" Clstrke). Hydrotheca (enlarged). (After Clarke.) 



4. Obelaria gelatinosa. ("Obelia castellata" Clarke.) Gonangium (enlargetl). (After Clarke.) 



5. Obelaria gelatinosa. Part of compound stem (enlarged). 



6. Silicularia peduneulala (Jaderholm) . Part of colony (enlarged). (After Jaderholm.) 



7. Silicularia pedunculata. Hydranth and pedicel (enlarged). (After Jaderholm.) 



8. Silicularia pedunculata. Gonangium (enlarged). (After Jaderholm.) 



Plate 25. 



Fig. 1. Silicularia rosea Meyen. Hydrotheca (enlarged). (After Meyen.) 



2. Silicularia rosea. Gonangium (enlarged). (After Meyen.) 



3. Silicularia reticulata (B.a.x\Xa.\xh) . Hydrotheca (enlarged). (After Hartlaub.) 

 '^. Silicularia reticulata. Gonangium (enlarged). (After Hartlaub). 



5. Silicularia atlantica (Marktanner-Tumeretscher). Part of colony (enlarged). (After Marktanner-Turner- 



etscher.) 



6. Silicularia repens {A\lma.ii). Hydrotheca and gonangium (enlarged). (After Hartlaub.) 



7. Silicularia hemispherica (Allman). Hydranth (enlarged). Part of C/faHenge?- type. 



8. Silicularia hemispherica. Hydranth and gonangium (enlarged). Part of CToMen^er type. 



9. Thaumantias inconspicua Forhes. Part of colony (enlarged). 



Plate 26. 



Fig. 1. Bonneviella grandis (Alliaa.n) . Hydrotheca (enlarged). 



2, 3. Bonneviella regia (Nutting). Hydrothecae of type (enlarged). 



4. Bonneviella regia. Hydrotheca and gonangia (drawn to same scale as fig. 2.) 



5. Bonneviella regia. Gonangium (much enlarged). 



Plate 27. 



Pig. 1. Bonneviella superba Nutting. Hydrotheca (enlarged). 



2. Bonneviella superba. Hydrotheca (natural size).' 



3. Bonneviella superba. Gonangia (enlarged). 



4. Bonneviella ingens 'Nutting. Hydrotheca (enlarged). 



' This figure illustrates the actual size of the largest hydrotheca that has ever been seen or figured by any writer, 

 80 far as the author has been able to discover. 



