48 ANNALS OF SCOTTISH NATURAL HISTORY 



occurred, it has been suggested that, in order to enforce the 

 moral of the story these plants tell, some of the details might 

 be of advantage in leading to searches for the same plants 

 in similar deposits. 



I. Arctic plant -bed at Hailes Quarry, four miles west of 



Edinburgh. 



The bed was found at the bottom of a series of deposits 

 which proved the existence of a lake in a hollow space between 

 boulder hillocks in the north-east corner of Hailes Quarry. 



The section exposed was as follows : 



1. 'Boulder clay, lying in a hollow of the sandstone rock. 

 Its apparent thickness in 1886 was only about 2 or 3 feet ; 

 but this increased to 12 or 14 feet as the rock was quarried 

 farther into the hollow trough. This boulder clay was hard, 

 stiff, almost rock-like, and crowded with stones of all sizes, 

 from a pebble to a boulder. It was doubtless genuine ground- 

 moraine matter. 



2. Immediately overlying the boulder clay was a layer 

 of large stones, which had evidently been washed out of the 

 boulder clay by the first water which filled the hollow after 

 the ice had melted off the land. 



3. Next occurred an Arctic plant-bed of fine sandy mud 

 or silt i or 2 feet in thickness, with many rootlets of plants. 

 In this silt the Arctic plants occurred, generally as thin 

 layers, and sometimes scattered through the silt as single 

 leaves, sometimes along with fruits and twigs. By careful 

 washing they could be easily separated from the silt. Along 

 with the Arctic plants there were found numerous remains 

 of a freshwater crustacean, including body segments, tail 

 segments, and supposed feet, and the more characteristic 

 mandibles with tooth-like processes resembling combs. These 

 have been recognised as those of Apus gladalis (or a kindred 

 species), now found only in freshwater lakes in Greenland and 

 Spitzbergen. 



4. Immediately above the Arctic plant -bed other silts 

 occurred, with seeds of Potamogeton in great numbers, and 

 many sprigs of light feathery mosses, and occasionally patches 

 of solid peat with other seeds of Potamogeton^ Menyanthes 

 (Bogbean), and Carices. There were found also little round 



