306 TESTACEA ATLANTIC A. 



dence, which might serve as a guide towards the solution of a 

 problem which requires to be approached from many different 

 directions. But the general character of the beetles, no less 

 than that of the plants, even though often evinced by species 

 which are totally distinct, is so marvellously similar through- 

 out the whole of these sub-African archipelagos, that it is diffi- 

 cult not to acknowledge the latter as but detached portions 

 (however isolated inter se) of a single geographical system. The 

 more sedentary nature of the Pulmoniferous Gastropods, as com- 

 pared with the majority of the insects, would lead us beforehand 

 to suspect that the truly indigenous exponents of the former 

 (unconnected specially with the 'inhabited districts ') would be 

 found to be less dispersed, or more localized, than those of the 

 latter, — as indeed is conspicuously the case even on tracts U'hich 

 are still unbroken ; therefore we need hardly feel surprised that 

 what is thus strongly indicated in other departments of the 

 Natural History, should be expressed somewhat more feebly in 

 the Terrestrial Mollusks. 



With the Cape Verde archipelago the Canaries, as regards 

 tlieir Grastropods, seem practically to be altogether disunited, — 

 three species out of the four which have been found in both 

 Grroups (namely the Helix lenticula, the Bulinius ventricosus, 

 and the Stenogyra decollata) having most likely been natural- 

 ized, and indeed the remaining one (the minute Patula pusilla') 

 perhaps falling under the same category. The Cape Verdes, in 

 point of fact, have a far closer connection with the Madeiras ; 

 for akhough it is true that the respective faunas have (so far as 

 has been observed hitherto) but six members in common, and 

 that there is an equal appearance of even these (with the 

 possible exception of the Patula pusilla) having been intro- 

 duced, nevertheless a marked coincidence exists between some 

 of the dominant types in the two archipelagos — as, for instance, 

 the Leptaxis section of the genus Helix, — which (although 

 present under species which are specifically dissimilar) would 

 tend, in some degree, to affiliate, as it were, the respective areas 

 of distribution.* 



Out of the 189 species which I would enumerate for the 

 Canarian archipelago, 13 have been found hitherto in a sub- 

 fossil state only ; and although this is no proof that they may 

 not occur recent likewise (for the majority of those which have 

 been met with in the conchyliferous deposits exist equally in a 

 living condition), they must nevertheless, of necessity, be re- 



' The six actual species which are common to the Cape Verdes and 

 Madeira are as follows : — Patula jmsilla, Lowe, Helix armillata, Lowe, and 

 hnticnla, Fer., Bulimus ventricosus, Drap., Stenogyra decollata, Linn., and 

 Achatina hihrica, Miill. 



