THE COLEOPTERIST IN TIREE. 



21 



company ifcs description — but proceed to a consideration of the 150 

 other species enumerated. Of these not more than perhaps eight can 

 be regarded as forming part of that North-Western group, which I 

 have elsewhere alluded to as the Keltic element in our Coleopterous 

 fauna, and ventured to suggest its priority of establishment to that 

 much larger group which, in the south and east of these islands has 

 succeeded and replaced it. Two species of these eight, viz., C. dathratus 

 and (>. blaiidits, are not recorded from England, and it is probable that 

 they no longer exist south of the border although both are found in 

 the west and north of Ireland. The other six — C. arreiifiis, B. jialU- 

 (lipennc, C d-liiieattis, B. sc/wnherri, S. //r/.st?».s, and S. lineelli(s are 

 species which, although they occur in England, are rare or absent in 

 the south, but become more frequent the further we go north and 

 west. As for the remaining 142 species, the majority of them are 

 commonly and equally distributed over the British Islands. We may, 

 indeed, call them dominant forms, that is, species which, by constitu- 

 tional vigour and physiological adaptability, have been able to over- 

 come those inequalities in environment, which have formed an 

 unsurmountable obstacle to their more susceptible fellows, and in this 

 way have succeeded in obliterating all evidence of their derivation and 

 all traces of their march. 



By such a power we find these dominant forms have penetrated to 

 the utmost verge of habitable land, and in those remote and storm- 

 swept rocks, which stand out in the Atlantic, the last outposts of our 

 Islands, they are still predominant. Thus of the 111 species recorded 

 by Prof. Hudson Beare and Dr. Joy from St. Kilda\ all but two ; of 

 the 35 from the Fair Isles'", all but one; and of the 11 from the 

 Flannan Isles^ the whole number are of these " dominant " forms ; 

 only two species in all these lists, ()tioiin/nchns blandas, and BanjnntKs 

 schiinlierri, being referable to the exclusively north-western group. 



We have still, however, to explain the presence of these or any 

 other beetles on a small island such as Tiree some 30 miles distant 

 from the nearest mainland. Many, in fact the majority, viay have 

 been transported by the wind. Such evidence as is afforded by the 

 phenomenon of innumerable beetles dropped into Llyn dur Arddu on 

 Snowdon, as recorded by Messrs. Tomlin and Sopp in these pagesS 

 or into the sea at Bridlington by the present writer^ prove that a 

 large proportion of the species found by Mr. Donisthorpe in Tiree 

 might quite possibly have reached it, if not by flight, at least wind- 

 borne when on the wing ; yet a remnant still remains, a small 

 minority, whose presence on this island cannot be so attributed. To 

 go no further than the first four beetles on the list — it is quite certain 

 that no Carabiis ever reached Tiree on the wing, and that for the very 

 obvious reason that they cannot fly. Therefore, unless we can accept 

 the supposition, to me incredible, that these Carahi arrived on the island 

 lurking in the crevices of some sea-borne log, or concealed in the canoes 

 of some primitive mariners, we are forced to the conclusion that they 

 have inhabited Tiree since that remote time when Tiree formed part of 



1 Aim. Scott. Nat. Hist., Hudson Beare and Joy, 1908, pp. 31-35. 

 •■i A7m. Scott. Nat. Hist., Hudson Beare, 1906, pp. 82-83. 



3 Ann. Scott. Nat. Hist., Hudson Beare, 1905, pp. 21-22. 



4 Ent. Record, vol. xiii. (1901), pp. 12, et seq. 

 ^ Ent. Record, vol. xxi. (1909), pp. 164, et seq. 



