238 APPENDIX. 
form of one of these “ birds’ heads,” and fig. 7 ¢, its 
position on the cell. 
FLUSTRA LINEATA, fl. I. fig. 1. 
In Flustre, the cells are placed side by side on an 
expanded membrane. Fig. 1 represents the general 
appearance of a species which at least resembles 
F, lineata as figured in Johnston’s work. It is 
spread upon a Fucus. Fig. a is an enlarged view 
of the cells. 
Fuusrra routacea. Pi. IL. fig. 2. 
We figure a frond or two of the common species, 
which has cells on both sides. It is rarely that the 
polypes can be seen in a state of expansion. 
SERIALARIA LENDIGERA. 2. I. jig. 10. 
NoraMiA Bursaria. Pl. I. fig. 11. 
The “tobacco-pipe” appendages, fig. 118, are of 
unknown use: they are probably analogous to the 
birds’ heads in the Cellularize. 
