92 ■ Proceedings of the Royal Physical Society. 



The macrospores of a number of recent Lycopods have been 

 examined for the purpose of comparison, and though as a rule 

 these are much smaller than those of Lepidodendra and 

 Sigillarim, their similarity to them is interesting and striking. 

 A few are figured on PL YL, Figs. 21-25. 



The fossil macrospores are divisible from external charac- 

 ters into three groups :— 1, smooth ; 2, apiculate ; and 3, those 

 with an equatorial zone. Among recent Lycopods, spores 

 occur answering to these three divisions. 



In our investigations we have collected material for exami- 

 nation from the four divisions of the Carboniferous Formation 

 as developed in Scotland, and in all — from the basement beds 

 of the Calciferous Sandstones to the uppermost beds of the 

 Coal Measures — spores have been plentifully found.^ 



The most suitable situations for collecting are outcrops or 

 exposed sections afforded by streams, sections on the sea- 

 shore, or exposures formed by railway cuttings, etc., where 

 the strata have become somewhat weathered. In such situa- 

 tions few of the impure coals or bituminous shales have 

 failed to yield spores or other organic remains. Such 

 weathered material, if free from bitumen, is easily prepared, 

 requiring merely to be first thoroughly dried, and then steeped 

 or boiled in water ; this usually reduces it to mud. 



Shales or fireclays highly charged with bitumen do not 

 dissolve so readily, and require to be crushed with the hand 

 under water. 



When the material has been reduced to as fine a condition 

 as it will admit of, it should be passed through a sieve, the 

 meshes of which must not be large enough to allow the 

 macrospores to pass through. The material should then be 

 sorted into different sizes by the use of sieves of different 

 coarseness. The rougher part may be redried, and the process 

 of reduction repeated. 



The finer assorted portion should be put in a basin of 

 water ; when agitated, and whilst in a state of suspension, 

 the lighter part should be decanted. This floating portion 



1 The Coal Measures of Scotland, viewed in their relation to the Coal 

 Measures as developed in Britain, are the equivalents of the lowest of the 

 three divisions of the English Coal Measures. 



