ItO AMERICAN JOURNAL 



In an appendix the following additional new species are 

 described : — 



Vitrina Letourneuxi. Helix ablennia. 



Zonites subplicatulus. Vertigo hriohia. 



Helix Challameliana. Hydrohia Challamelliana. 

 " Bastidiana. 



In the appendix a recapitulation of the species is given, 

 numbering 319, being 234 more than the number enumerated 

 in Terver's work, and 194 more than the catalogue of Morelet. 

 A map of Algiers is next given, colored to represent those 

 parts of the country thoroughly and superficially explored 

 and unexplored for shells, respectively. The latter exhibits 

 by far the largest surface, and the thoroughly explored region 

 is comparatively small. 



The species of Morocco and Tunis are then enumerated and 

 compared with those of Algiers. The third chapter of the 

 appendix treats at length of the geographical distribution of 

 the species, and is illustrated by a colored map showing the 

 position of the littoral, mountain, and high plateau faunae, with 

 a tabular view of the species of the mountains and of the 

 valleys. 



The fourth chapter shows that the species of the Algerian 

 provinces do not approach those of the Canaries, Madeira, 

 Sicily, or Central Africa, but belong rather to the Spanish 

 fauna. In proof of this proposition, lists of the shells of the 

 above islands are given. M. Bourguignat concludes, from the 

 very distinct faunas possessed by the Canaries and Azores, 

 that each archipeligo (once a single large island) has its own 

 particular centre of creation, and that they did not at any time 

 join the African Continent. Among 254 Sicilian species enu- 

 merated, 62 are also Algerian, but many of these are cosmo- 

 polite species. The species of Spain number 300, of which 

 more than half are found also in Algiers. 



In a fifth chapter the author examines the Malaco-strati- 

 graphical principles governing the distribution of species of 

 the European system. He says that — 



" 1. Between the 35th and 46th degrees of north latitude is 

 found a zone of creation, and this zone coincides with a series 

 of mountain ranges extending from the Atlantic Ocean to the 

 Caspian Sea in Asia. 



" 2. That to the north of this zone the species distributed 

 over the vast central and northern regions of Europe originate 

 entirely within this zone. 



" 3. That to the south, on the contrary, each species has a 

 localized existence, and remains unchangeable in its habitat 

 and its mode of habitation." 



