44 



THE ZOOLOGIST. 



former of these attains to the altitude of about 850 ft. above 

 Gloucester city, which is itself about 50 ft. above the sea-level, 

 high spring tides still continuing further up the river to occa- 

 sionally as far as Upton-on-Severn, near Malvern. This belt 

 terminates upwards at the point where the graceful climbing 

 Clematis vitalba ceases to flourish, for, although it maybe seen in 

 the greatest luxuriance up to 600 ft. or so, it can occasionally be 

 met with in the shape of dwarfed and stunted specimens for 

 another 300 ft. higher still, within the protection of woods, 

 deserted stone-quarries, and other sheltered situations. From 

 50 ft. to 600 ft. above sea-level it climbs over the trees and 

 hedges in such profusion that it constitutes in places quite 

 a characteristic feature in the landscape, and by reason of its 

 great luxuriance affords an almost subtropical aspect and ap- 

 pearance. The range of mean annual temperature of this zone 

 is from 50° to 47° Fahrenheit. 



The mid-agrarian zone of Dr. Watson rises above the pre- 

 ceding belt, and embraces all the summits of the hills upwards 

 of 900 ft., and most of the escarpment plateau as well, where 

 the distinctive Cotteswold fauna and flora predominate. It only 

 occupies, however, an exceedingly circumscribed area in all. 

 Now, although, as it will be perceived, the altitude is not great, 

 I hope to show in the following account of the local Terrestrial 

 Mollusca that something can be accomplished even in this 

 restricted perpendicular area in studying their vertical distribu- 

 tion, and in the influence of altitude upon their morphology. It 

 must be considered, however, only as an outline of my observa- 

 tions. I have not included the fluviatile forms for the simple 

 reason that I have as yet not paid particular attention to them 

 in the Cotteswolds, where they are apparently not very con- 

 spicuous in consequence of the scarcity of the necessary element, 

 springs and small brooks being plentiful enough, but pools 

 and ponds almost entirely absent, and what few there are at the 

 higher levels becoming mostly dried up during the summer 

 months. 



The geological formation of the Cotteswolds consists of the 

 oolite, which contains an abundance of lime ; consequenly Ter- 

 restrial Mollusca are exceedingly numerous both as regards 

 species and individuals. And the beautiful beech woods which 



