maturity, by the lateral pressure of one frond on another. I can- 
not say anything to the collector of specimens in praise of the 
beauty of this production ; what it has in that way it keeps con- 
cealed, or reserves for microscopic eyes. 
Fig. 1. Cluster of fronds of RrvULARIA PLICATA, on a piece of rock :—the na- 
tural size. 2. One of the fronds, cut vertically to show the hollow centre. 
3. A vertical portion of the gelatine, with imbedded filaments. 4. Some 
of the filaments removed and pressed asunder :—the latter figures more or 
less highly magnified. 
