228 Proceedings of the Royal Physical Society. 



in our woods and gardens, which any one, on casting their 

 eye over these two small cases, will at once recognise. 



I may remark that a similar deposit of leaves to this one 

 exists not far from Bournemouth, viz., at Alum Bay, Isle of 

 Wight, and it is quite possible that some connection existed 

 at a remote period of time between the two localities, although 

 the sea now separates them ; but, of course, this can only be a 

 matter for conjecture. 



The clay in which these leaves are found is generally of a 

 soft and plastic nature, and it requires to be of a certain degree 

 of hardness before good specimens can successfully be ex- 

 tracted by splitting. If too hard again, the clay is brittle, and 

 the specimens are frequently obtained only in a fragmentary 

 state. Some attention is therefore required in preparing the 

 clay for manipulation. Mr Gardner describes this process, 

 and he, being a regular summer resident at Bournemouth, had 

 ample opportunity and time for selecting perfect and hand- 

 some specimens ; but a casual visitor of only a day or two, 

 such as myself, must, generally speaking, be content with 

 only second-rate specimens. 



The casts only of many of the leaves remain, the fibre hav- 

 ing vanished. In not a few cases, however, the fibre is intact 

 in a carbonised state, but when exposed to the air, rapidly 

 crumbles away. The clay itself in which the leaves are held 

 is, when dry, also inclined to pulverise, so that the only way 

 of preserving the specimens is to dip them in a weak solution 

 of isinglass or size. 



II. On the Occurrence of Colias edusa in Scotland during the 

 Summer 0/ 1877. By E. F. Logan, Esq. 



Colias edusa is a remarkable insect in this country, on 

 account of the occasional superabundance of its individuals, 

 witliout our being, hitherto, able to assign any known cause 

 for the sudden increase in its numbers. During last summer 

 this beautiful insect appeared in unusual abundance. In 

 ordinary seasons it is quite unknown in Scotland, while it is 

 rare even in the south of England ; but last year it app( ared 



