54 
of another existing form unless it can be proved or shown to be 
highly probable that the one descended from the other, this other 
itself remaining meanwhile unchanged. It is necessary, there- 
fore, to guard against the error of supposing that the arbitrarily 
chosen forms we see placed as species, with varieties subordinated 
to them are the true parents of those varieties ; for whilst the 
varieties were being formed the parents themselves may have 
been undergoing modification, and therefore the so-called species 
and their varieties may be all equally varieties of some common 
possibly extinct form. In the present case, all that I mean to 
convey is, that, reasoning upon the fact of much local modifica- 
tion in A. Onca, we are constrained to infer that other closely 
allied forms have been derived from a pre-existing one nearly 
resembling them ; and this might have been either A. Onca or 
the common parent of A. Onca and its subordinates*. 
Genus Gymnocerus, Serv. 
Serville, Ann. Soc. Ent. Fr. 1835, p. 84. 
In this genus both sexes have eleven joints to the antennae. 
According to Serville, the 6 has the terminal joint very long. 
Amongst the species which I propose to include in the genus, 
some have this joint as long as the tenth, others much shorter; 
and it is always relatively shorter in the $ than in the S . All 
the joints are naked ; but the third in some species, and the 
fourth in others, are more or less thickened at the tip. The 
body is convex and rather broad, and the elytra somewhat more 
gradually rounded to the apex than in Anisocerus. 
This genus was omitted in Mr. White's ‘ Catalogue of the 
* Some entomologists, however, believe that a local varietj^ is an original 
creation equally with a species. Dr. Schaum, an author of high reputation, 
says, in discussing a case of local variation similar to the present one (Ber- 
liner entom. Zeitschr. 1861, p. 398), that many pairs of a species were 
originally created, and that, as there would be original differences amongst 
the individuals according to locality, so we have, at present, local varieties. 
This view will recommend itself to some minds by its extreme simplicity ; 
for the excessive complexity of the relationships between existing varieties 
and species, on the other view above stated, repels by its difficulty of 
unravelment. In no case does the remark of Bacon so well apply, to the 
effect that the subtlety of nature far exceeds the subtlety of man’s intellect. 
But Dr. Schaum’s view ignores the fact that many local varieties shade off 
into mere individual variations or differences, such as we see occurring 
amongst the offspring of the same parents, making it extremely probable 
that local varieties or races have been derived by ordinary generation, with 
modification, from pre-existing forms. The hypothesis of the persistence, 
under the same conditions, of a local variety from the time of its creation 
is also quite at variance with the great mass of evidence, supplied by 
geology, of great migration and dislocation of species during the glacial 
and other epochs. 
