284 Quarterly Journal of Conchology. 



2 7 species of Achatina are attributed by Woodward, are not now 

 considered to possess one ; not on account of errors in localities, 

 but because all the species are referred to other genera — the genus 

 Achatina being now restricted to the large phytophagous African 

 species, e.g., A. fuUca. The additions that have been made to our 

 knowledge of the particular regions will be stated more particularly 

 under each. It may, however, be well to say generally that 

 whilst the additions to the faunas of Europe, North Africa, and 

 Asia Minor, of Tropical Africa, of Philippines, of the United 

 States, and, to a less extent, of South America, have, though con- 

 siderable, not been such as to materially modify general conclu- 

 sions, the contrary is the case with regard to India, many of the 

 Polynesian Islands (including New Caledonia), Australia, and ■ 

 Mexico. 



We adopt, generally, the great divisions of Dr. Sclater, sub- 

 dividing them into regions of smaller extent, and we would make 

 the general remark that whilst on continents a vast extent of land 

 is sometimes comprised in a single region, very small islands must 

 often be separately treated. 



With regard to the boundaries of regions there is one mis- 

 conception as to which we must v/arn our readers, that of thinking 

 that they are sharply defined. This is only true with regard to 

 some islands, and even with them there are often cases in which 

 the fauna has in some way overstepped a narrow strait and spread 

 to the neighbouring mainland, as in the case of Florida, which 

 has received a large immigration of West Indian species. On 

 continents a sharp boundary is very rare, and the rule is for one 

 fauna gradually to give way to another, as there are seldom 

 natural obstacles forming perfect barriers ; even in the case of the 

 Tropical African Province, perhaps the best defined of any, 

 Abyssinia is a sort of border land in which such purely African 

 groups as Limicolaria and Pclla are found together with 



