2 TEST ACE A ATLANTIC A. 



although far less so than either their plants or their Coleoptera 

 (the former of which have been accurately investigated by Dr. 

 Seubert, Mr. H. C. Watson, and others), the Laud Mollusca of 

 the archipelago, owing to the observations of ^Nlorelet, Drouet, 

 and Grodmau, have perhaps been better worked-out than the 

 generality of the departments of which, in the aggregate, the 

 Natural History is made up. Yet, judging from the analogy of 

 the more southern groups, it is impossible to believe that the 

 nine islands which compose tliis widely-scattered assemblage 

 (and which are mapped out, as it were, into three divisions 

 topographically distinct) should possess no more (or even no 

 considerable nwniher more) than the 71 Pulmoniferous Grastro- 

 pods which have been brought to light, for the most part, by 

 the united exertions of the three independent explorers to whose 

 published voliunes I have just called attention. Eather should 

 we suspect that a longer and more careful research, in distant 

 spots and at a high altitude, such as have shown themselves to 

 be so prolific at the Madeiras and Canaries, will sooner or later 

 augment the list to (if not more) at least 100 species. 



Perhaps however it will be objected that the Cape Verdes, 

 on the other hand, which include a more extensive area still, 

 and are represented by no less than ten islands, have as yet 

 yielded but -iO Gastropods, and that, moreover, to a larger 

 number of investigators. But to this I would reply, that the 

 cases are not parallel ones ; for the unhealthy and poverty- 

 stricken Cape Verdes have become so deteriorated and dried-up 

 since the destruction of their forests, and after all have been 

 visited for periods so short and insufficient by each successive 

 adventurer, that the several departments of their Xatural His- 

 toiy have not stood a fair chance of a proper examination ; 

 whereas the Azores, which enjoy one of the dampest atmospheres 

 in the world and are more or less clothed with a rich vegetation 

 (even though seldom aboriginal), present all the conditions 

 except those of soil (which however is much the same in the 

 U'hole of these Atlantic archipelagos) for the full development 

 of the Terrestrial Mollusks ; so that I do uot believe that a safe 

 comparison can be instituted, from the data as hitherto ascer- 

 tained, between the respective faunas of those two particular 

 gToups. Far rather should we be content to contrast the 

 Azorean fauna with that of the Madeiras (which akeady num- 

 bers 176 species, well separated from each other), or with that 

 of the Canaries, — which, although less perfectly investigated, 

 has been found to contain (even hitherto) 189. 



AiVTien we consider the geographical position of the Azores 

 with reference to Europe, the centre of the group being in 

 much the same latitude as Lisbon, and when we also bear in 



