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EXPLANATION OF PLATE XXV. 



Fig. 1. A magnified view of a whole small specimen of Notamia bursaria. 

 Fig. 2. a. Front view of a portion of a branch. 



b. Back view of the same. 

 Fig. 3. Front view of the initial portion of the stem. c,c". Initial cells. d,d'!. Pri- 

 mary cells. 



b. Back view of the same. 



Fig. 4. Enlarged view of polype cell and tobacco-pipe process or cup. 

 a. Retractor muscles of polype. 

 b,b f b. Extrusor muscles ? 



c. Cup, shewing the muscles by which the beak is elevated and depressed, and 



indistinctly a hollow viscus contained in the cup. 



d. Front view of the beak of the cup. The spot in the centre is the point of 



attachment of the depressor muscles. 

 Fig. 5. a, b. Diagrams to show how the branches are constituted of two series of cells, 



each of which has a cup or pair of cups at the bottom of the series. 

 Fig. 6. A diagram to explain the mode of derivation of each series from one or other 



of the primary cells. 



