SHORTER NOTES 117 
fern of northeastern and central Mexico which has 
hitherto passed as Cheilanthes gracillima Eaton. From 
that species of the western United States it differs, 
Mr. Maxon finds, in its greater size, in having hairs 
instead of scales on the upper surface of the frond and 
in the characters of its scaly covering. 
Prof. Vaughan MacCaughey' has published an ecolog- 
ical survey ,of Hawaiian pteridophytes. The most 
striking feature of the Hawaiian fern flora is the 
extraordinarily high proportion of species which are 
found nowhere except in these islands—123 out of 
190.5 This is due to the long isolation of the Hawaiian 
archipelago. The endemic species are very irregularly 
distributed among the different islands. Kauai has the 
most; Oahu is next; Hawaii, though much the largest 
in area, has the fewest. This, Prof. MacCaughey points 
out, furnishes striking corroboration of the generally 
accepted belief that the western islands are older and 
have been longer isolated than the eastern. It is just 
in the regions supposed to be geologically the oldest 
that the richest fern-flora is found. 
Prof. MacCaughey divides the ferns into two | series 
of groups, one based on their distribution in point of 
altitude, the other on their preference for wet, medium, 
or dry habitats. He closes with an annotated list of 
all the species known to occur on the islands. 
Some Currousty Cur Specimens oF DryoPTERIs 
Boortm—In August last while searching for Dryopteris 
hybrids in Washington, Mass., my son found a very 
MacCaughey, Vaughan. An ecological survey of the Hawaiian 
Perdophy tos Journal of mooper 6: 199-219. Nov. 30, 1918. 
* The ter, not Prof. MacCaughey, is doubtless responsible for 
the deathenane ucthe text that es ma of 190 species are endemic— remark- _ 
able percentage indeed! 
