racters above given: we possess specimens scarcely five inches 
long, including the root, and all intermediate grades to eighteen 
or twenty inches. The caudex is generally small and indistinct, 
perpendicular, clothed with numerous thick wiry roots. The 
largest of our sterile fronds is two and a quarter inches broad, 
divided almost to the base into spreading segments finely ser- 
rated at the margins; often the midrib is prolonged for some 
inches into a tail-like point, proliferous at the extremity. The 
fertile fronds are always much longer than the sterile one, nar- 
rower, linear and entire, the whole margin formed of the closely 
compacted and coadunate involucres, from which the columella 
or receptacle (its base clothed with capsules) is much exserted. 
It is the general prolongation or exsertion of these bristle-shaped 
receptacles that has suggested the English specific name. 
Fig. 1. Sterile and fertile fronds (from the same root),—wmat. size. 2. Fertile 
frond,—nat. size. 3. Portion of a segment of the sterile frond. 4. Section of 
a fertile frond. 5. Involucre laid open, showing the capsules surrounding the 
columella. 6. Capsule :—adl magnified. 
