xii INTRODUCTORY REMARKS. 
species which, in the usual acceptation of the term, would be called 
incligenous : 
TOME COMTCOP IEA Ss ATRIA ORE Raa say tHe 94 
Di Briveneletie kj Alea Melis ise OM kee iS 88 
Di GDA hag is Mls OSs hs a ee at 71 
fy a NCep a bids: ie leah Bent leks. Sperone anh 6. 
Oi FLCLOP OMNI. a Pale So haa i a begcts celine abies, agbtalg 4] 
Gs PEO COROT Se Mea a eats, Shi a SE Gan Daca ae 30 
i. PSCUQOLTURCRR ? och Tes eee ae ee 19 
Si PAMOphAga eo eee 8 a Re ee, 19 
Dy COPD YLOCEV OEE. os ric ce eee soe: RE 13 
Lee ar iL 0 la rai RN Se we Mn Sie anna ek 13 
LP aeEeceomenben en itt Aare pen oh AMO SB A oe 4 
AD. ary Gra ep li pe ilens Peds Abas Bh Sie HR ght 4 
460 
Here then we have two Catalogues to judge from; and it is 
remarkable how nearly they correspond, both in their arrangement 
and numerical proportions: hence, whether we regard the entire one, 
or that which is confined to the more evidently indigenous species, it 
matters not,—for the general conclusions will be the same. 
That the Water-beetles and Longicorns should be so feebly repre- 
sented, in an island almost clothed with forests and abounding in 
streams, is not a little remarkable; yet such is the case, for there 
are apparently but three of each in Madeira proper which can be re- 
garded as absolutely indigenous. In Porto Santo indeed, and on the 
Dezertas*, there would seem to be but two water-beetles ; whilst in 

* Tt is an important fact for those naturalists who are studying the questions 
of insect-migration, that there should be even a single water-beetle on the 
Dezertas,—for there wre no streams there. On the southern island there is not 
any water at all, so that none of these creatures can of course be found upon 7; 
but on the two northern ones, a few small pools to receive the drainings of the 
surrounding soil, after rain, have been (I believe within a comparatively recent 
period) artificially formed : nevertheless in these basins (the contents of which, 
T imagine, must well nigh evaporate during every hot season) the Agabus nebu- 
losus and Hydroporus confluens (both common European species) absolutely 
teem. It is generally supposed that the Hydradephaga are more difficult of 
transport than the members of most other families ; but this is more apparent 
than real, for it must be remembered that they are very active and powerful in 
flight, and that many of them are not killed by a considerable immersion in the 
sea. ‘* Although perhaps at first sight,” says Mr. A. Murray (in the Hdinburgh 
New Phil. Journal, vol. ii. p. 170), “a water-beetle may not seem a very pro- 
bable insect to be introduced by man, still, in point of fact, there are few classes 
of insects more likely to haye their range extended in this way. A ship fills its 
water-casks at a stream, or well, in one country ; if they are not exhausted by 
the time it reaches its destination, in another, the old water is started out, and 
the casks re-filled: so that, supposing a few larvee or eggs of water-insects to get 
ito the barrels when being filled, they may be introduced as colonists into any 
