Januaky 29, 1904.] 



SCIENCE. 



167 



The Bermuda Islands are compcsed of 

 porous limestone with a thin covering of 

 soil. The nature of this substratum pre- 

 vents the accumulation of water excepting 

 a few brackish ponds near the level of tide- 

 water. Conditions of moisture and expo- 

 sure are very uniform, hence plant asso- 

 ciations are not large, nor do they vary 

 widely. The largest ecological area com- 

 prises in a general way all the hillsides and 

 slopes that have sufficient soil to support 

 a large vegetation. Their appearance is 

 somber on account of the large number of 

 cedars which cover them. Two species of 

 Lantana (called the Bermuda sage-brush) 

 are associated with the cedars, and crab- 

 grass and cap e- weed cover the ground. 

 Tall oleanders are marginal to the cedar 

 groves and Yucca alsifolia is abundant 

 along the cliffs. A second area comprises 

 the rocky shores along the ocean, charac- 

 terized by gnarled forms of Conocarpus 

 erectus, Borrichia ariorescens, Solidago 

 sempervirens and Opuntia Tuna. A third 

 area is formed by the sandy beaches and 

 small dunes along the south shore. The 

 sea blackberry, Sccsvola lobelia, is the most 

 abundant form and Ipomoea pes-caprce is 

 almost as common, trailing its long vines 

 over the sands and helping to bind them 

 together. Secondary in importance are 

 Cakile aqualis, Toumefortia gnaphaloides, 

 the golden-rod mentioned above and the 

 sea ox-eye, Borrichia arhorescens. These 

 mesophytie and xerophytic areas are most 

 prominent, but there are two types of 

 swamps to be noted. The Devonshire 

 marsh was apparently once a large pond 

 but there is little water left. Two species 

 of Spliagn-um, Proserpinaca palustris, 

 Typha latifolia and Eichornia occupy the 

 lower pools. Hydrocotyle Asiatica and 

 Herpestis monniera are rooted in the mud. 

 Osmunda Cinnamomea and 0. regalis are 

 abundant in somewhat drier places, while 

 in the dry, peaty soil Pteris aquilina cor- 



data, the cedar, palmetto and dog-bush are 

 most common. The mangrove swamps 

 about small inlets of the sea constitute the 

 second hydrophytie area. The aerial roots 

 from the limbs of Ehizophora Mangle and 

 the curving prop-roots add considerable 

 interest to these swamps. The seeds begin 

 to grow on the trees, then drop into the 

 mud, their pointed ends fixing them up- 

 right, while the growing roots soon pene- 

 trate the soil and a pair of leaves appear 

 at the upper end. Avicennia nitida, the 

 false mangrove, is associated with the true 

 and along the tide-water margins are Sali- 

 cornia fruticosa, Statice Lefroyi. Sesuvium 

 Portulacastrum and Coccoloia uvifera. 



A Lichen Society of a Sandstone Riprap: 

 Bruce Fink. 



A general discussion of the conditions 

 under which the society has developed and 

 is now growing, including some statement 

 as to amount of moisture in various por- 

 tions of the riprap, amount of disintegra- 

 tion at various points and amount of ex- 

 posure to sun and wind. Following this 

 . is a consideration of the ecologic condi- 

 tions and resulting spermaphytic flora in 

 the area, and the effect of these surround- 

 ings on the composition of the lichen so- 

 ciety. Next in order is given a list of the 

 lichen species of the society, followed by a 

 discussion of the conditions under which 

 each species is growing and the adapta- 

 tions of each species to these conditions. 

 Brief comparisons are made between this 

 society and three others found on sand- 

 stone, and herein are shown some very 

 marked responses between ecologic condi- 

 tions and structural adaptations. 



I'elation of Soil to the Distribution of Veg- 

 etation in the Pine Region of Michigan: 

 E. B. Livingston. 

 The study here reported is of about 



fifteen townships lying in Roscommon and 



