17 
synepigony—these are no longer serviceable when we attempt the 
delimitation of genera. And 1 venture to affirm, without fear of 
contradiction, that no living systemaiist has anything really tangible 
to supply in their place. Even if we possessed a complete history and 
pedigree from the time of the first appearance of the insect world on 
our planet—a more wildly chimerical supposition even than that in 
which I indulged by way of introducing the first part of my subject — 
I should still be justified in doubting whether such history and pedigree 
would furnish us with really satisfactory data for “ natural genera.” 
Supposing we said, every group which has been syngamic within the 
la«t 10,000 years, or within the present geological epoch, shall be 
called a genus; is it in the least likely that the evolution of each would 
have proceeded by anywhere near sufficiently equal stages to give us 
“ genera” which we could with any show of reason co-ordinate? Ur 
if, instead, we said, the last six, or the last twelve “ species ” which 
have branched oft from each stirps shall constitute our “ genus ” ; can 
we believe that the result would be any more satisfactory? A stranded 
waif in the “ struggle for existence,” like Tanagra ( Odezia ) atrata or 
Aplasta orwnana, would have to go into a genus with the most ill- 
assorted company, while large, recent, compact genera like Eupithena 
would be split up on the most minute characters—if, indeed, we had 
any morphologists competent to find “characters” serviceable for 
differentiation at all. 
No, let it be stated most emphatically that a “genus" is purely a 
grouping of convenience —or of inconvenience, if you will. I must 
confess that to me it is quite un-understandable how an entomologist 
possessing such a grasp of biology and evolution, and such a clear idea 
of the “ species ” problem as does Mr. Tutt, should take such a singular 
and unorthodox view of the functions of the “ genus ” as we know to 
be the case. Mr. Tutt’s ideal is that the genus ought to be the next 
evolutionary grade to the species. But, as I have pointed out on 
another occasion, this would really result in giving us probably no 
more than two species to any genus, and generally one species only; 
for it must be very rarely indeed that an evolution branch has been 
literally trifurcate—/.<?., that three species of a group have become 
differentiated absolutely synchronously; and of course if all, or nearly 
all evolution has proceeded by bifurcation, only the newest pair along 
each line will be congeneric, and all the uncles, grand-uncles, etc., (so 
to speak) will be accorded separate generic rank. Abundant illus¬ 
tration can be found of this point even within our restricted British 
fauna ; and many of the illustrations will be so obvious as to appeal 
readily to a gathering of entomologists most of whom have not dived 
deeply into morphology. Naturally my thoughts fly to the 
Geometridce, though the other families would furnish just as many 
examples. Take the genus Hypsipetes ( Hydriomena ). It is a very 
“ natural ” genus, both in the imaginal and the earlier stages. Yet I 
suppose we are all conscious of the closer relationship which exists 
between trifasciata ( autiunnalis ) and rnberata than between these two 
and sordidata (furcata ). Ergo, the two first-named give us the next 
grade to the species and consequently the “ genus,” and we must create 
a new genus for sordidata. Probably in actual fact even this is not all; 
the group is strongly represented in North America, and it may 
xix. 
