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stunted condition. The fronds are not half the normal size 

 of those I have found on ledges of high lime content in the Wall- 

 kill Valley, or on the Mississippi river cliffs in Iowa, or in the 

 Harlem valley in Putnian and Dutchess counties. With it is 

 much maidenhair spleenwort, more healthy in appearance; 

 evidenth' this species can prosper with much less lime. I have 

 seen Walking Fern on a limestone boulder, of high calcium 

 content, a glacial erratic on granite, in Sussex County, N. J., 

 which was perfectly normal, though ten miles away from the 

 nearest ledges of such rock. The wonder in both cases is at 

 the establishment of the Walking Fern in the first place, so far 

 from its usual haunts. 



The other plant, the Prickly Pear Cactus, was found on 

 thin soil covering the basalt of Preakness Mountain, a mile 

 northeast of Pine Lake. Various evidences pointed to the cer- 

 tainty that the ridge was once in open pasture. The red cedars 

 were dying from the increasing shade of oaks and other hard- 

 woods which were re-establishing themselves. Phlox subulata, 

 which usually prefers the sun, persisted, in thin unthrifty stands 

 in this shade. Prickly Pear is not rare in northeastern New Jer- 

 sey and the Lower Hudson Valley; I know a dozen stands of 

 it, but it always seems strange to see a plant which one asso- 

 ciates with the arid Southwest in our northeastern hardwood 

 and mixed forest areas. I believe the accepted explanation is 

 that the cactus and probably other plants of arid climes migra- 

 ted north after the close of the last Glacial Period, during a time 

 of low rainfall, as indicated by aeloian deposits in the Missis- 

 sippi valley and other evidence; and that since the climate has 

 become more humid, the plant has retreated to dry, sandy 

 places, such as Nantucket Island, eastern Long Island and 

 southern New Jersey, and to lofty, rocky, almost bare hill- 

 tops, or similar situations. 



The small colony of Prickly Pear which we found on Preak- 

 ness Mountain was no more happy than the lime-starved 

 Walking Fern ; it was not spreading, showed no blossom buds, 

 and some of its fleshy branches were withering. Evidently 

 the shade, increasing yearly since the last cutting, or since the 

 ridge was in pasture, is gradually killing it out. Its tenure in 

 this locality seems likely to be short. I have seen two or three 

 other small stands on this ridge, and only one, on a dry open 

 ledge, was observed to bear blooms and fruit. 



