XII THE COLEOPTERA OF MADEIRA 257 



Otiorhynchus, Brachycerus, and twenty other genera of 

 Curculionidse, comprising more than 300 South European 

 and North African species, are absent from Madeira, with 

 two exceptions. One is the Trachyphlo&us scaler, a widely- 

 spread European insect often found in ants' nests ; and 

 this, with the case of the Thorictus, renders it probable 

 that ants'-nest species have some unusual means of distri- 

 bution, which are by no means difficult to conceive. The 

 other exception is that of the genus Acalles, which has a 

 number of Madeiran species, all peculiar, and is very 

 abundant in all the Atlantic islands. Now we have first 

 to remark that Acalles is an isolated form, but is allied 

 to Cryptorhynchus, which is often amply winged ; so that 

 we may easily suppose that its introduction to Madeira 

 took place before it became completely apterous in Europe. 

 In the second place, we have the fact that many of the 

 species are confined to peculiar herbaceous and shrubby 

 plants, in the stems of which they undergo their trans- 

 formations, and which habit would afford facilities for 

 their occasional transmission in the egg or pupa state 

 across a considerable width of ocean, while a fragment of 

 dry stem containing Qgg or larva might possibly be carried 

 some hundred miles or more by a hurricane. Such sup- 

 positions would not be admissible to account for numerous 

 cases of transmission, but, as will be seen, this is almost 

 the only example of a genus of large-sized apterous 

 European beetles occurring in Madeira. 



Pimelia, Tentyria, Blaps, and eighteen other genera of 

 Heteromera, comprising about 550 species of South Europe 

 and North Africa, are totally absent from Madeira, with 

 the following interesting exceptions : — two common species 

 of Blaps, which are admitted to have been introduced by 

 human agency, and three species of Meloe, two of which 

 are European and one peculiar. The means by which the 

 apterous, sluggish and bulky Meloes were introduced is 

 sufficiently clear, when we remember that the minute 

 active larvae attach themselves to bees, insects of exceed- 

 ingly powerful flight, and more likely than perhaps any 

 others to pass safely across 300 miles of ocean. That the 

 solitary exception to the absence of wholly apterous 



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