THE SUBJECT NOT EXHAUSTED 419 
group. With attention directed to the number of species 
actually existing, it is probable that the half-score described 
by Bate and Westwood as belonging to the British fauna 
will soon prove to be but the nucleus of a far larger com- 
pany. By accepting the view that no parasite has more 
than one species of host, we may greatly simplify the 
otherwise bewildering task of naming specimens, and so 
far leave the mind at leisure to grapple with the other 
numerous and intricate difficulties connected with this 
little-known tribe. 
