300 LIST OF WORKS, ETC. 



tion of these animals, especially in South America, says the 

 terrestrial Pulmonobranchiata are much more abundant in the 

 warmer regions of the different quarters of the globe than in 

 the more temperate parts, while the aquatic species are more 

 abundant in the latter than in the former. 



He observes that the terrestrial species gradually diminish 

 in number as we proceed from the warmer regions towards the 

 pole ; and as we ascend from the plains to the tops of moun- 

 tains. Out of the 156 species which he found in South 

 America, 137 were found between the 11th and 28th, 28 be- 

 tween the 28th and 34tb, and only 13 between the 34th and 

 45 th degrees of south latitude; and 126 species were found 

 under 5000 feet, while only 4 were found above 5000 feet and 

 below 11,000 feet, and 6 at more than 11,000 feet above the 

 level of the sea. 



V. 



LIST OF WORKS AND PAPERS ON BRITISH LAND AND FRESH- 

 WATER MOLLUSCA. 



Joshua Alder. Notes on the Land and Fresh-water Mollusca 

 of Great Britain, with a revised List of Species. Mag. 

 Zool. and Botany^ ii. 101. (Aug. 1837.) 



George J. Almann. Description of a New Genus of Pulmo- 

 nary Gasteropods, Geomalacus. Ann. and J\lag. N. H. 

 xvii. 297. 1846. 



Ch. AsHFORD. List of Land and Fresh-water Mollusca of 

 Ankworth, Yorkshire. Zool. xi. 481. 1854. 

 Description of a new British Limnea. Ann. and Mag. N, 

 H. xvii. 396. 1846. 



W. Baird. Long suspended Vitality of a Snail. Ann. and 

 Mag. N. H. vi. 68. 



ir. Baker. A Shower of Snails. Zoo/, ix. 3187. 1851. 



