PLATE XII. 
Figs. 1, la . — Obelia geniculata (p. 23). 
Fig. . 1. — A colony ; natural size. 
Fig. la . — Portion of a colony ; magnified 15 diameters. 
Figs. 2, 2 a. — Thyroscyplius ramosus (p. 24). 
Fig. 2. — Portion of colony ; natural size. 
Fig. 2 a . — Portion of the same; magnified 15 diameters. 
Figs. 3, 3 a.^Halecium beanii (p. 12). 
Fig. 3. — A colony ; natural size. 
Fig. 3a. — Portion of a colony with female gonangia; magnified 15 diameters. 
