LITHOLOGY. 67 



together that water sinks readily through it predominates, a 

 circumstance which indicates pretty conclusively that it is the 

 dryness of the limestones rather than their chemical composition 

 which is the chief source of attraction. Several of them are to be 

 met with upon the coast sand-hills in the neighbourhood of Red- 

 car: a few of them are found in the vicinity of the basaltic dike 

 in Cleveland : more of them amongst the subcalcareous portions 

 of the Inferior Oolite, as at Boltby and especially where in the 

 Howardian tract the calcareous character of the interposed band 

 is most clearly marked. Some of the commonest of the 

 Subxerophilous species are scattered at intervals over the 

 sandier parts of the Central Valley and may be found in such 

 stations as the Ouse side along the Clifton Ings, the banks of 

 the Swale at Topcliffe, of the Tees between Stapleton and Croft 

 and the gravelly soils of the neighbourhood of Bedale and 

 Kirklington. 



M. Thurmann gives for the portion of Central Europe which 

 includes the Vosges and the Jura both a list of the indigenous 

 plants and an account of their distribution with regard to the 

 subjacent rocks. Comparing the British flora as a whole with 

 that of this region or indeed with that of any other part of the 

 interior of Central or Southern Europe we see even by glancing 

 over the mere list of names how conspicuously with us the 

 damp-loving element predominates. When a British and Foreign 

 Cybele is written, a work giving an account of the distribution 

 of British plants through foreign countries and of the relation 

 of our indigenous flora to that of Europe as a whole, this is one 

 of the points which its author will have to explain to us and 

 illustrate for us in detail. Out of fifty species which M. Thur- 

 mann gives as being within his limits the commonest plants 

 which are characteristic of dysgeogenous tracts we have in North 

 Yorkshire as indigenous plants eight species only : out of the 

 fifty species which he names as the commonest plants which 

 are characteristic of the eugeogenous tracts within his limits we 

 have in North Yorkshire thirty-one species. 



April t888. 



