MADEIEAN GROUP. 57 



II. MADEIEAN GROUP. 



OF all the Atlantic Islands, those which constitute the Ma- 

 deiran Group have been by far the most carefully examined ; and 

 I think also that it is not too much to affirm that their species 

 are the most isolated, as regards structure, and peculiar. The 

 observations of the Kev. E. T. Lowe were extended, at intervals, 

 over a period of at least forty years ; and they have been well 

 supplemented by those of Mr. Leacock, Senhor J. M. Moniz, 

 the Eev. E. B. Watson, the late Mr. Bewicke, the Barao do 

 Castello de Paiva, Senhor N. Marcial, and others ; added to 

 which, the occasional visits to the archipelago of distinguished 

 European naturalists, such as Dr. Albers, Professor 0. Heer, 

 M. Hartung, and Sir Charles Lyell, have combined to increase 

 our knowledge of the fauna, and to throw additional light on 

 many an obscure problem with which it is connected. My own 

 researches were commenced in 1 847 ; and during the thirty years 

 which have since elapsed the Natural History of Madeira, under 

 one or another of its departments, and in connection with that 

 of the more southern clusters, has been well-nigh constantly be- 

 fore me. 



In reviewing the Pulmonata of this archipelago (which num- 

 ber, in all, according to my computation, 176 species), the most 

 salient fact which meets us at the outset consists in the marvel- 

 lous segregation of its several members within areas of the most 

 limited extent. Thus, to take the Terrestrial species only, if we 

 remove the European and North-African ones (represented by 

 the Limaces and Testacellce, the Hyalina cellaria and crys- 

 talling the Patula rotundata and pygmcea, the Helix pul- 

 chella, aspersa, pisana, caperata, armillata, lenticula, and 

 lapicida, the Bulimus ventricosus, the Stenogyra decollata, 

 the Pupa umbilicata^ the Balea perversa, the Achatina acicula, 

 and lubrica, and the Lovea follicidus), which in all probability 

 have become accidentally naturalized, and which are no more 

 characteristic of the Madeiras than they are of the Canaries and 

 the Azores ; out of the 138 which remain there are absolutely 

 only 7 which have found their way beyond the limits of the 



