1913] The Ottawa Naturalist. 95 



In the denser' shaded stations the fern was in company with 

 Asplenium Filix-femina and Cystopteris fragilis. 



Before proceeding to a consideration of the cliff ferns, it 

 will be necessary to give a short description of a station already 

 mentioned, namely, Credit Forks. This location is situated in the 

 northern part of Peel County; there the Credit River has cut 

 through the Niagara escarpment, leaving an exposure of clay 

 and rock of about 345 feet in height. Commencing below the 

 level of the Credit River a slope of red clay extends upward for 

 175 feet; overlying this is about 20 feet of Medina sandstone, 

 while the top of the section furnishes an outcrop of 150 feet of 

 almost vertical limestone of the Niagara formation. The clay 

 elope is covered with a talus of blocks of sandstone and limestone 

 fallen from the cliff above, and in the crevices of these rocks 

 manv ferns find roothold. 



Cryptogramma Stelleri (Gmel.) Prantl. (Slender Cliff 

 Brake). Found usually on narrow, moist, shaded ledges of 

 limestone cliffs.* It roots, in company with moss, in detritus 

 derived from the weathering of the rock. It is a frail and delicate 

 species, very sensitive to sun and to lack of moisture. 



Pellaea atropurpurea (L.) Link. (Purple Cliff Brake). 

 In crevices of limestone cliffs; not nearly so sensitive to lack of 

 shade and moisture as the former species. It is often found in 

 dry situations under full illumination. It thus shows closer 

 affinities with Pteris. 



The two cliff brakes we have just considered are both found 

 in the vertical limestone section of the Credit Forks' escarpment. 

 It is worthy of note that they are entirely absent from the blocks 

 of rock which cover the clay slope. 



Scolopexdrium vulgare Sm. (Hart's Tongue). This fern 

 is found abundantly in Europe; in England it is reported as 

 hanging from old ruins and even drooping from the stone curbs 

 of wells. In America, however, it is exceedingly rare; it is found 

 in Tennessee and New York, while in Ontario it is confined to the 

 district between Collingwood and Owen Sound. At Woodford, 

 near Owen Sound, it is found rooting in soil on the top of lime- 

 stone rocks and cliffs; there it is associated with Polystichum 

 Lonchitis and Poly podium vulgare. The ferns are shaded by 

 paper birch, small maple and beech, with an occasional hemlock. 

 It grows at OWen Sound from crevices in the walls of fissures in 

 limestone rocks ; but under these conditions, however, it does not 

 thrive as well. 



Polystichum Lonchitis (L.) Roth. (Holly Fern). Has 

 nearly the same distribution in Ontario as Scolopendrium and its 

 habitat is practically the same. 



