Plate XV. 



Fig. 47. Gonothyrœa gracilis. 



A. Natural size. 



B. Hydrotheca and gonophore. 



C. Large gonophore. 



D. Much elongated hydrotheca and gonangium. 



E. Elongated gonangium. 



Fig. 48. Gonothyrœa inomata. 



A. Natural size. 



B. Portion of branch showing hydrotheca?. 



C. Gonophores. 



Fig. 49. Obelia borealis. 



A. Natural size 



B. Portion of stem showing mode of branching and hydrothecse. 



C. Gonophore. 



Fig. 50. Obelia dichotoma. 



A. Natural size. 



B. Portion of stem showing hydrothecae and gonophores. 



