Roy. Hncy. of Erliv. ] 



[Vol. XXX. 



Fig. 121. — Isle nf May. One of the ])uols on an exposed part of tlie islam! iie;ir tlie lij^'iitliouse. A dwarf 

 form of Heleocharis palustris, with which H. uniglumis is mixed, overgrows the entire area of tlie iiool. 



Fig. 122.— Isle of I\Iay. Precipitous clilfon the west of the island, consistin,:,' of black columnar hasiilt. 

 Tlie cliir is inhabited In^ great numbers of sea-birds, wliose nests are placed chielly ui.nn tlie exposed 

 ends of the coluimis, the black rock being wliitened by the droppings from the birds. It is nearly 

 low water, and tlie light zone at the base of the cHlf is caused by tlie abundance of Halanida', etc. 



Mr Gkokge Wes'I'. 



[Plate ^\.— Referral to uii j'ttyts 173 to 177. 



