PLATE XVI. 
Figs. ], la . — Halisiphonia megalotheca (p. 31). 
Fig. 1. — Portion of a colony growing on the stem of another Hy droid. 
Fig. la. — Portion of the same ; magnified 10 diameters. 
Figs. 2, 2a. — Lafoea fruticosa (p. 34). 
Fig. 2. — A colony ; natural size. 
Fig. 2a. — Portion of a colony; magnified 15 diameters. 
