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X. The Carabid genus Pheropsophus : Notes and descrijJ- 

 tions of new species. By Gilbert J. Arrow, F.E.S. 



[Read May 1st, 1901.] 



Plate IX. 



The well-known genus Plicr opsonins is in many ways one 

 of special interest. One of the three or four genera 

 known to have the power of producing a detonation when 

 molested, its many species all have the sharply contrasted 

 black and orange colouring so commonly prevailing in 

 groups possessing special defensive endowments. Although 

 it occurs throughout the hot regions of the globe except in 

 oceanic islands, the majority of its members are African, 

 America and Australasia together having only three or 

 four widely-distributed but ill-defined species. The pre- 

 dominant Oriental species also have a very wide distribu- 

 tion and great range of variation, but the African forms 

 (in common with those from India and Arabia) present a 

 different condition, appearing to be more or less restricted 

 in their range, and although in certain directions variable 

 in coloration, presenting specific differentiations which are 

 practically constant ; so that, though upon a preliminary 

 survey the marking appears to be subject to almost endless 

 variation, a minute examination resolves the insects into 

 numerous series characterized by apparently insignificant 

 but almost invariable differences of coloration which are 

 found to be correlated to differences of form and structure. 



The fact is probably that Africa and South- Western 

 Asia form the original home of these insects, which 

 spreading from thence all over the world, have met with 

 new conditions in which forces which had operated against 

 their variation and geographical expansion were absent. 

 There is perhaps additional evidence of this in the fact 

 that many of the species in the former countries are with- 

 out wings, or have them in some stage of degeneration, 

 while all those found in other regions are active insects 

 with well-developed wings. The less deviation of these 

 from the normal should imply that they are of more recent 

 date, but that the atrophy of the wings indicates no very 

 great antiquity is shown by its occurrence in different 



TRANS. ENT. SOC. LOND. 1901.— PART III. (SEPT.) 14 



