73 



where there is a law there must be an exception to it; 

 and that, consequently, exceptional cases, if not exceed- 

 ingly numerous, should never pervert our belief from an 

 otherwise presumptive truth. 



This dwindling-down of size has seldom failed to 

 attract my attention, more or less, in almost every island 

 which I have hitherto had an opportunity of exploring : 

 space, however, will not permit me to dwell upon many 

 instances. I have already adverted to the diminished 

 stature of Anthonomus ater, Mshm, and Ceutorhynchus 

 contractus, Mshm, in Lundy Island, the first of which 

 scarcely ever reaches, on that rock, more than half its 

 natural bulk. The late Mr. Holme, of Corpus Christi 

 College, Oxford, in like manner, captured the com- 

 mon Calathus melanocephalus, Linn., and Olisthopus 

 rotundatus, Payk., in Scilly, the former of which 

 seldom exceeded two lines, and the latter two and a 

 half, in length : and he also recorded, that the Bolito- 

 chara assimilis, Kby, is invariably smaller in those 

 islands than it is in the neighbourhood of Penzance *. 

 The Vanessa Callirhoe, Fabr. (a geographical analogue of 

 the Red Admiral Butterfly f, so common in our own 



* Trans, of the Ent. Soc. of London, ii. pp. 59, 62. 



t Considering that the true Vanessa Atalanta, of more northern 

 latitudes, does occasionally occur around Funchal, it may be reason- 

 ably contended that the fact of its coexistence (on the same spot) 

 with the V. Callirhoe is strong presumptive proof that the latter is 

 a true species, and no climatal or insular modification of the former. 

 And so, judging from a distance, and without local evidence to ex- 

 plain this phenomenon, I should have concluded myself : never- 



E 



