178 



the upper surface of which is black in the JL. timiduSi and 

 white, tinged with greyish towards the base, in the Irish 

 species. On looking to their osteology, some slight differ- 

 ences are observable in the head ; the comparatively more 

 horizontal direction of the lumbar vertebra in the Irish hare 

 is conspicuous, and likewise the relative shortness of its tail, 

 which, as first recorded by Mr. Eyton, contains three 

 vertebraB less than that of the EngUsh species, 13 only being 

 possessed by the former, and 16 by the latter animal. 



The occasional whiteness of fur in the Irish hare is 

 believed by the author to be a consequence of age, and not 

 regulated by the law that is understood to affect the Alpine 

 hare, which is considered to change its dark summer fur to 

 white at the commencement of every winter. 



The economy and habits of the Irish hare, which generally 

 correspond with those of the common species, are, together 

 with a comparative description of form, colour, &c., very 

 fully detailed in this paper. 



Mr. Robert Mallet read a paper " on an hitherto un- 

 observed Force of Elevation and Degradation." 



The author maintains, that the forces producing geologic 

 changes are either mechanical or chemical, and that the 

 reaction of these forces, when co-existent, as is usually the 

 case, often gives rise to a third order of forces, which may 

 be denominated molecular forces, or those which, without 

 altering the atomic composition of bodies, affect the arrange- 

 ment and aggregation of their particles— modify their specific 

 gravity— their action on light, heat, electricity, &c., and 

 produce the varied differences of ductility, hardness, brittle- 

 ness, &c. &c. "While chemical and mechanical forces have 

 been applied to geology, those of this latter class have been 

 almost wholly overlooked. 



Of the several known molecular forces, those producing 

 change of volume and of specific gravity are perhaps the 



