38 PALMER : 



In the third edition, published in 1853, the note is changed to 

 "Limestone rocks and cliflFs ; Great Valley; rare." Keller 

 and Brown give six localities in as many counties, and one of 

 them is the " Brooke's Mill " of Dr. Darlington. Another is 

 " Conshohocken," on the authority of Charles E. Smith. 

 The writer has seen it nowhere except at Brooke's Mill, where 

 he had sight of it during a trip with the late Lewis Palmer, in 

 1880. It grew rather sparsely on the top of a much- weath- 

 ered, well-shaded limestone rock. Never abundant there, it 

 was for many years sought in vain by some botanists, and 

 no doubt it had been practically exterminated by those who 

 loved but too well to "lend an air of verisimilitude to an 

 otherwise bald and unconvincing narrative " by the exhibition 

 of a specimen or two. However, these rare species come and 

 go in a mysterious manner. The spores become disseminated 

 generally, and when they alight in congenial surroundings 

 some of them give rise to prothallia. The prothallia lurk 

 unseen, and eventually send up sporophytes. So it is, that 

 after an interval of a few years the fern is re-established in the 

 old, the original, the altogether fitting spot. It was not, 

 therefore, a matter of very great surprise to learn that A. ruta- 

 vmraria had been seen within a few years not far from 

 Brooke's Mill. One does not hesitate to mention this, for the 

 reason that the locality is already on record. Also, it has 

 come to pass that the local collectors have now mostly reached 

 that stage of enlightenment which guarantees a proper self- 

 denial in the presence of rare ferns. Lastly, the name 

 "Brooke's Mill" expresses nothing to the non-elect. You 

 shall not find ii on any modern map, and only the oldest of 

 the native inhabitants in the region could tell 3'ou where it is. 

 And, if by any combination of favorable circumstances the 

 neophyte arrives, he will have earned his view of the fern 

 before he obtains it. 



A species worthy of passing mention is the bladder fern 

 {Filix bnlbifera). This fern grows in damp and shady rav- 

 ines, and may be overlooked because it resembles somewhat 



