PLATE VI. 
Tig. 17.—M. ternata. Enlarged portion of colony from California. 
Much like the preceding except that the lateral avicularia are often lacking. 
Fig. 18.—M. gracilis Busk. Habit sketch, natural size. 
Fig. 19—M. gracilis. Portion of a branch enlarged to same scale as 
figs. 14 and 17, showing the greater length of the zoecia, the large flabellate 
scutum (se.), the relatively small size of the avicularia (av.), and the shape 
and position of the two sorts of root chambers (r. d. and r. ch.) similar to 
those of M. ternata. X 30. 
Fig. 20.—M. gracilis. Portion of an ocial internode showing develop- 
ment of avicularia (av.) on the front of the zocwcium close to the owcia 
(oe:).) 30: 
Fig. 21.—M. gracilis. Dorsal view of the zoecium at the bifurcation of 
a branch (bi. z@.), showing the lateral adjoining zowcia (lat. z@.), and 
root chamber (r. ch.) with upward extending rootlet (wu. r.). X 30. 
Fig. 22.—M. occidentalis Trask. Habit sketch of a single branch to 
show method of branching. Somewhat diagrammatic. 
Vig. 23.—M. occidentalis, A few internodes enlarged to show size of 
avicularia (av.), position and size of scutum (sc.), the nature of the jointed 
spines (sp.), and the crossed spines (c. sp.). Drawn to the same scale as 
figs. 14, 17, and 19. X 30. 
Fig. 24.—M. occidentalis. An oecial (0e.) internode consisting of five 
zocecia. X 30. 
Fig. 25.—M. occidentalis. Lateral view of a zoecium, showing a root 
chamber (7. ch.) from which there extends a downward extending rootlet 
(Gena, 2 clk 
