Calkins. — Hydroids. 
PLATE 5. 
Fig. 24. Sertularella fabricii. Nat. size. a. Hydrotheca. X 80. b. Hydro- 
caulus. X 18. 
Fig. 25. Hydrallmania falcata. Nat. size, a , b. Front and side views of 
hydrotheca. X 80. 
Fig. 26. Aglaophenia struthionides. Nat. size. a. Hydrotheca. X 80. b. 
Gonosome (corbula). X 18. 
Fig. 27. Plumularia setacea. Nat. size. a. Hydrocaulus. X 18. b. Hydro¬ 
thecae and nematophores. X 80. c. Nematophore, much enlarged. 
Fig. 28. Plumularia echinulata. Nat. size. a. Hydrocaulus. X 18. b. Hydro- 
theca and nematophores. X 80. c. Nematophore, much enlarged. 
Fig. 29. Sertularella nodulosa. Hydrocaulus. a. Hydrotheca and hydranth, 
the latter contracted in a characteristic manner, b. Gonosome. 
