1911] Girault, Species of Trichogrammatil(B (Hymenoptera). 165 



be represented by but one name. The differences between the two 

 as described are merely in degrees of adaptation, the expectation 

 under the different conditions in the habitat. Parexorista che- 

 loniac is a more typical case. There is no reason why a series of 

 individuals of a species from a chance locality should agree in all 

 habits with a series from another locality and that they are found 

 to differ in this respect shows merely the effect of different de- 

 grees of adaptation, fulfills the expectations and denotes no dif- 

 ferences of specific value. To settle the matter it is but necessary 

 to see whether or not the two series interbred. The American and 

 whether or not the two series interbreed. The American and 

 European series of minutum do interbreed and must therefore be 

 the same species as that term must be understood from every 

 standpoint. 7 



We may call groups of individuals of a species biological or 

 physiological species for convenience sake, but fundamentally the 

 term so applied is a confession of ignorance and expresses only 

 some adaptation or some (perhaps incompletely observed) func- 

 tion, which, when fully investigated, we should expect to appear 

 some time in the history of any chance group of individuals of the 

 same species whatever may be its origin. The sum of the matter 

 is that specific difference have so far always been expressed mor- 

 phologically ; the morphological change or difference) is an index 

 of a change or difference in the germ, but not necessarily a cer- 

 tain index as in the case of what are called varieties. 



LITEKATURE SPECIFICALLY CITED. 



1911. Howard, Leland Ossian and William F. Fiske. Lull N'o. 91, 

 Bureau of Entomology, U. S. Department of Agriculture, 

 Washington, D. C, pp. 87, 136, 143 and 236 ff 



Urbana, 111., Aug. 21. 1911. 



On the contrary, the second European species mentioned by Howard 

 and Fiske (lb., p. 257) in reality the second species of Trichoyramma, which 

 has recently been described by myself as Pentarthron euproctldis and which 

 differs morphologically from the two series of minutum would not interbreed 

 with any member of the two series in question. 



