504 



NATURE 



[April 2^, 1878 



five or six to the Madeiras and Canaries, and about one 

 to the Canaries and Cape Verdes ; whilst between the 

 Azores and Canaries there are only about five, and be- 

 tween the Madeiras and Cape Verdes about one. Moreover 

 there are strong reasons for suspecting that some even 

 of these (perhaps, indeed, most of them) may have been 

 accidentally transported amongst the islands, through 

 indirect human agencies, at a comparatively recent date ; 

 so that we are driven to conclude that, so far as the 

 absolute species are concerned, of which their aboriginal 

 faunas are respectively made up, the groups are practi- 

 cally almost independent of each other. And yet, in 

 spite of this, I have had occasion to insist more than once 

 upon the many characteristic types which, under the 

 aspect of totally different but nevertheless allied species, 

 permeate to a greater or less extent the entire 'province,' 

 giving to it an amount of utiity, through its several com- 

 ponent parts, which it is scarcely possible not to recog- 

 nise." (P. 563.) 



The ^^ Atlantis hypothesis" was clearly present to 

 WoUaston when he wrote : — 



"There may doubtless be many explanations, perhaps 

 equally plausible, of these phenomena, but I must con- 

 fess that none commends itself so thoroughly to my mind 

 as the possible breaking up of a land which was once 

 more or less continuous, and which had been inter- 

 colonised along ridges and tracts (now lost beneath the 

 ocean) which brought into comparatively intimate con- 

 nection many of its parts, even whilst others, though 

 topographically near at hand, were separated by channels 

 which served practically to keep them very decidedly 

 asunder. It is on some such principle as this that I 

 would account for the Canaries appearing to be not only 

 as widely removed from Madeiras as perhaps even the 

 Cape Verdes are, but (whilst further to the south) to pos- 

 sess a fau7ia of which the ' Mediterranean ' element is 

 much more traceable. This latter circumstance, which is 

 shadowed forth likewise by the Coleopterous statistics, is 

 by no means a fanciful one, whole groups which are indi- 

 cative (more or less) of Mediterranean countries, but 

 which have no single representative elsewhere in these 

 Sub-African archipelagos, being quite at home at the 

 Canaries." (P. 565.) 



An evolutionary phase of mind must have prevailed 

 with WoUaston when he penned the following sen- 

 tence :— 



" It is quite clear that the depression of certain tracts, 

 and the upheaval of others, would produce an amount of 

 disturbance in the fauna which could not fail to show 

 itself in some one way or other which would afterwards 

 become more or less decipherable ; and I cannot con- 

 ceive much difficulty in picturing the kind of change 

 which might be brought about by the isolation of a 

 cluster of individuals on a small rock, destined hence- 

 forth to become the habitat of a race which would, we 

 may feel well nigh certain, rapidly mature for itself some 

 slight distinguishing mark." (P. 566.) 



But he quickly returns to his former state, and 

 adds : — 



" Considering how unmistakable the evidence is for 

 the variability (in this particular sense) of many of the 

 Atlantic types — a 'variability' so decided that a slightly 

 different phasis has been assumed in certain of the 

 Archipelagos, for nearly every separate island and iso- 

 lated rock, it may sound, perhaps, somewhat paradoxical 

 to speak, nevertheless, of their apparent freedom from 

 further change ; and yet if there is one fact more dis- 



tinctly shadowed forth than another it is, without doubt, 

 their present stability.'''' (P. 566.) 



Further on he continues : — 



" After the most rigid and conscientious inquiry, I am 

 bound to add that the 'developments,' so called, which 

 might well be supposed to have been slowly elaborated, 

 are iii any) simply inappreciable^ (P. 567). 



However widely we may disagree with Mr. WoUaston' s 

 conclusions on the qua;stio vexata of species and va- 

 rieties, his critical remarks are of great importance from 

 the large series of specimens examined by him, and the 

 fact that the types themselves were, in many cases, in 

 his possession. 



In an admirable lecture "On Insular Floras," by Sir 

 Joseph Hooker, delivered before the British Association 

 at Nottingham in 1868, he described the Madeiran flora 

 as composed of two elements, the one clearly allied to 

 that of the shores of the Mediterranean, the other totally 

 different, and allied to none other but what is found in 

 the Canaries and Azores, which he designated " the 

 Atlantic Element." 



That Sir Joseph Hooker's researches on the flora and 

 WoUaston' s observations on the insect and molluscan 

 fauna of these Atlantic islands should bring out precisely 

 similar results, will seem the less surprising when we 

 remember the direct connection and interdependence 

 existing between plants and insects, the latter acting as 

 the great fertilising agents to the former ; whilst the 

 dependence of land snails upon plants is equally manifest. 



All the difficulties raised by WoUaston as to tke rare, 

 peculiar, and isolated forms described by him were met 

 and answered by Sir Joseph Hooker ten years ago. 

 Assuming these minute islands to be relics of an older 

 and once larger land-area which had been gradually 

 reduced by subsidence, he pointed out that such a 

 change, by contracting the area would intensify the 

 struggle for existence. He showed that they were not 

 new forms likely to increase and multiply, but rather old 

 forms dying out. Also that in this e.xterminating process 

 man was even a more destructive agent than the sub- 

 sidences of land. For instance Madeira when discovered 

 was so densely wooded that the settlers set fire to the 

 forest and the fire raged for seven years, no doubt exter- 

 minating many species and reducing the number of 

 others proportionately. 



In Porto Santo rabbits had proved even more destruc- 

 tive than man ; whifst in St. Helena, the introduction of 

 goats in 15 13, had almost exterminated the forests and 

 the subsequent replanting of the island with exotic plants 

 prevents the remaining indigenous vegetation from 

 resuming its sway. 



Whatever be the extent of area which we reclaim from 

 ocean for our ancient "Atlantis," it is evident that 

 formerly intercommunication existed between the Azores, • 

 Madeira, the Canaries, the Cape Verdes, and Southern 

 Europe in Miocene times, for Prof. O. Heer considers 

 some of the Helices of Porto Santo to agree with those 

 of the Swiss molasse. 



The poet's dream may therefore well be realised by the 



geologist : — 



" Which tells, great pictured Continent, of thee 

 O blest Atlantis ! can the legend be 



