PLATE XVIII, 
Figs. 1, la, lb. — Cryptolaria humilis (p. 39). 
Fig. 1 . — A colony ; natural size. 
Fig. la. — Portion of a colony ; magnified 8 diameters. 
Fig. lb . — The same, after maceration in caustic potash; the axial tube with its hydro- 
thecse is seen in its entire extent, freed from the close investment of the 
peripheral tubes ; magnified 10 diameters. 
Figs. 2, 2a . — Cryptolaria abyssicola (p. 40). 
Fig. 2. — Portion of a colony ; natural size. 
Fig. 2a. — Portion of same ; magnified 10 diameters. Two gonangia are here seen. 
