THE ENTOMOLOGIST. 83 
the Lepidoptera into Rhopalocera (butterflies, or day-flyers) 
and Heterocera (moths, or night-flyers). It was no sooner 
proposed by Boisduval than it was recognised as a most 
convenient arrangement, and adopted very generally. The 
antenne in this order are always conspicuous, and _ their 
clubbed or non-clubbed tips are easy of observation, and 
associated with other important characteristics which sepa- 
rate the two groups. The Sphingide, however, by their 
crepuscular habit, and their antenne thickening towards the 
end, though terminating abruptly in a point, bring the two 
groups in Close relationship, and diminish their value; while 
the Castniide, on the one hand, and the Hesperide, on the 
other, so intimately connect them, that it becomes almost a 
matter of opinion as to whether the former should be con- 
sidered butterflies, or the latter moths. Urania and other 
abnormal genera make the relationship of the two groups 
still more perplexing. On antennal structure alone—whether 
we consider the clubbed or non-clubbed tips according to 
Boisduval, or the rigidity, direction, and length, which Mr. 
Grote deems of greater importance—two primary divisions 
cannot be based. If we take the spring or spine on the hind 
wings, which is so characteristic of the Heterocera, we meet 
with the same difficulty, for a large number of moths do not 
possess it, while an accepted Hesperian (Euschemon Rafflesia, 
Macl.), from New South Wales, is furnished with it. Nor is 
there any one set of characters which will serve as an infallible 
guide to distinguish moths from butterflies; and the number 
of moths described as butterflies, and the fact that Kirby 
considers the position of Barbicornis, Threnodes, Pseudo- 
pontia, Rhipheus, Agiale, and Euschemon, included in his 
‘Synonymic Catalogue of Diurnal Lepidoptera’ as doubtful 
butterflies, gives sufficient proof of the truth of the statement. 
Between all classificatory divisions, from variety to kingdom, 
the separating lines we draw get more and more broken in 
proportion as our knowledge of forms, past and _ present, 
increases. Every step in advance towards a true conception 
of the relations of animals brings the different groups closer 
together, until at last we perceive an almost continuous 
chain. Even the older naturalists had an appreciation of 
this fact. Linnaus’s noted dictum, “Natura saltus non 
facit,” implies it; and Kirby and Spence justly observe that | 
“It appears to be the opinion of most modern physiologists 
