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its comrades, we can easily understand how the varied 

 processes of accidental transportation would operate to 

 increase the range of a creature which differs so essen- 

 tially, in many respects, from them. It is indeed, not 

 unfrequently, brought down, at the present day, by 

 human agencies from the mountain-slopes ; for, since 

 the cutting of faggots is one of the few sources of live- 

 lihood to a large proportion of the poor of Funchal, 

 numerous insects of subcortical and lichen -infesting 

 tendencies are subject to be naturalized (provided they 

 can adapt themselves to the change) in altitudes lower 

 than their normal ones : so that there are many chances, 

 even a priori, in favour of the T. Lowei having over- 

 spread, whether by natural or artificial means, a wider 

 area than its congeners. I believe that there is no such 

 thing as a Tarphius in the Canarian Group : neverthe- 

 less, singularly enough, a representative, which is more 

 akin to the T. Lowei than to any other hitherto dis- 

 covered (and which was imagined until lately to have 

 been the sole exponent of the genus), namely, the 

 T. gibbulus, Germ., occurs in Sicily. From which data 

 we arrive at this significant fact : that, whilst Madeira 

 proper is, without doubt, the original centre of the 

 Tarphiiy two species (one of which is, likewise, Ma- 

 deiran) are found in Porto Santo, to the north-east of it ; 

 whilst a third makes its appearance in an island of the 

 Mediterranean. 



The genus Acalles presents a nucleus of species in the 

 Canaries, moulded on a very large pattern. A closely 



G 2 



