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under the former contingency the determination of species 

 would become practically well nigh hopeless, it is far 

 from unlikely that we shall eventually hail the latter as, 

 after all (at any rate to a certain extent), the more con- 

 venient of the two. Look, for instance, at the great 

 genus Pterostichus, which has nearly 200 representatives 

 in Europe alone : true it is that its several sections 

 (Pcecilus, Argutor, Omaseus, Corax, Steropus, Platysma, 

 Cophosus, Pterostichus proper, Abase, Percus, and Molops), 

 although easily recognized in the mass, do unquestionably 

 blend into each other; yet I believe that it has arisen 

 from a too rigid promulgation of the generic theory 

 that they have not been retained as separate. And this 

 opinion may be rendered somewhat more plausible, 

 from the knowledge that certain of the Pterostichi (the 

 Argutors, for instance) approach so closely, in their 

 trophi, to Calathus, as to be hardly discernible from it ; 

 which latter genus is scarcely distinguishable (struc- 

 turally) from Pristonychus, a form which, in its turn, 

 leads us on towards another type. Who would have 

 imagined, again, some fifty years ago, that the widely 

 distributed groups, Calosoma and Carabus, were not 

 thoroughly detached inter se ? yet what naturalist now 

 can draw an exact line of demarcation between them ? 

 And so it is with numerous others, which it is needless 

 to recall. The practical inference, however, from the 

 whole, is this : that if genera must be rejected because 

 they are not homogeneous and isolated throughout, the 



