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IX. A Revision of the genus Tarucus. By G. T. Bethune- 

 Baker, F.L.S., F.Z.S. 



[Read April 4th, 1917.] 



Plates XIV-XX. 



A YEAR or two ago Mr. Rowland-Brown questioned me 

 on the distinctness of the European species of the genus 

 Tarucus, Moore, and my answer was that the clasping organs 

 of the males were different, and that therefore I considered 

 the species were distinct. This conversation led me to 

 look up the whole matter afresh, and in doubtful cases 

 to make more preparations of the genitalia, thus bringing 

 to light the fact that one of the Indian or a new species 

 occurred in Egypt and Algeria as well as the well-known 

 and first-described species theojjhrastus, Fab. ; this dis- 

 covery involved a more extended research of the Indian 

 species of this complex and very difficult little genus. 



My investigations have caused me great searchings of 

 heart, not on the distinctness of the species themselves, 

 but rather on the questions " What is a species? " and 

 " On what characters are we to form species ? " It is quite 

 obvious that in this genus it is scarcely possible from the 

 pattern alone to decide, in certain cases, which is which, 

 and yet it is equally certain that Butler's and Moore's 

 species, which de Niceville called so strongly into question, 

 are quite distinct from theophrastus, their clasping organs 

 are quite different, and they also are different from each 

 other in addition to differing from that species described 

 by Fabricius. 



I have endeavoured to make a table of differences in 

 the pattern between the species, but in vain, for whilst 

 there is a general look that enables one to assign a name 

 to the specimens, and as a rule the assignment is right, 

 yet it often breaks down ; for instance, I have specimens 

 from Egypt and from Algeria that I had placed under 

 theophrastus, but their clasps proved that they were in 

 reality a new species altogether; again, specimens from 

 Lahej (Arabia) and from India, that I had no doubt were 

 nara, proved by their genitalia to be theophrastus. There 



TRANS. ENT. SOC. LOND. 1917.— PARTS II, III, IV (mAY '18) T 



