PLATE 1 
EXPLANATION OF FIGURES 
All figures represent Renilla amethystina Verrill. 
1 to 4 Successive phases.of the waves of peduncular peristalsis; figure 1, the 
beginning; figure 2, later stage; figure 3, nearly completed; figure 4, completed. 
5 to 8 Successive phases of the wave of rachidial peristalsis. 
5 Colony seen from the inferior side with the peduncle elevated and out of 
focus. The rachidial wave has just started from the peduncle and appears as a 
pair of indentations on the lobes of the rachis next the peduncle. 
6 A later phase of the rachidial wave in which the indentations have reached 
the midrachis; view of the inferior surface of the colony. 
7 Rachidial wave in about the same phase as that seen in figure 6, but viewed 
from the superior surface. 
8 Rachidial wave as a pair of indentations approaching the apical margin, 
where the indentations will fuse and the wave cease. 
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