MADEIRAN GROUP. 59 



vexata of ' origin '), — a processwhich might, and probably would, 

 be again and again repeated until there were no ' species ' at all 

 left (as such) either to enumerate or to monograph ! Of course, 

 within reasonable limits, every monographer is at liberty, in the 

 first instance, to use his own judgment as to what forms are spe- 

 cific ones and what varietal ; indeed he must of necessity do 

 so ; but where there is an abundance of material before him, 

 and he possesses a personal knowledge of the principal habitats 

 concerned, he is not likely to make many very serious blunders 

 as regards the value of the characters upon which he has to ad- 

 judicate ; for where the forms in question cannot be connected 

 by intermediate links (either recent or fossil) and are at once 

 readily separable from their congeners., although he has a per- 

 fect right to speculate on their origin in any way (and to any 

 extent) he pleases, he certainly would not be justified in impos- 

 ing his ^lesses upon others, or in citing the organisms as other- 

 wise than specifically distinct. In recording what we see, facts 

 and fancies must be kept apart ; for if they are permitted to be 

 mixed up unnecessarily in descriptive Natural History, it does 

 not require much foresight to perceive tliat the result at last 

 will become so sliifting and untrustworthy that, sooner or later, 

 they will be mutually destructive of each other. ^ 



After what has he&n said, it will readily be admitted that 

 * varieties ' likewise (properly so called) — i. e. forms which may 

 be connected with their parent types, but which nevertheless 

 have a sufficient permanence about them to be recognisable as 

 modifications, or races, within their respective areas, — no less 

 than species, must have a significant place in a catalogue like 

 the present one. And to return to the subject of segregation, if 

 we take into account the varieties also, we shall find that the 

 same tendency is shadowed forth, and in a manner even more 

 conspicuous still. Thus, for instance, the eminently plastic Helix 

 polyniorpha, Lowe, of which I have registered no less than 

 thirteen easily separable (but more or less overlapping) states, 

 may be well-nigh said to possess a slightly different phasis— not 

 only for each of the larger islands (on which there are several of 

 them), but for every minute rock, particularly those around 

 Porto Santo, which has hitherto been landed upon and explored : 

 a fact which bears witness to the same principle of localisation, 

 only in this instance exemplified by ' varieties,' instead of by the 



' Acting upon this principle, I shall reserve until the closing section of 

 the present volume any mere speculations which I may venture to offer on 

 what will have previously been recorded, and which must be taken for what 

 they are worth, — for they may, or may not, commend themselves to the minds 

 of others. All that we have to do now is to look to ouv facts, and to use every 

 endeavour to make them strictly accurate. 



