LEPIDOPTERA. — SPHINGID. 367 
as one of the five primary sections of the Lepidoptera) into five 
groups, of which four are represented by the genera Macroglossa, 
Smerinthus, Acherontia, and Sphinx, whilst the fifth has for its type 
the very distinct genus Zygena. This arrangement cannot, however, 
be considered a natural one, since the four first-mentioned genera 
possess distinctive characters, znter se, of far slighter value than those 
which separate Zygzena from any of them; in other words, these four 
genera are but types of genera in one family, whilst Zygena is the 
type of a distinct family. The larvee of the Smerinthi are, it is true, 
covered with minute granular tubercles, and the head is conical, but 
surely these are the characters of a genus, and not of a stirps or 
family. In a very few species the caudal horn of the larva is nearly 
or entirely obliterated, as in the North American Sphinx Coniferarum 
(Abb. and Smith’s Lepid. of Georgia, vol. i. p. 42.), a species closely 
allied to Sph. Celerio and Plebeia, placed by Mr. Stephens in the same 
group with the true elephant moths, but which, in this respect, is as 
far removed from them as the Sphinges Euphorbize and Galii, which 
have been miscalled spotted elephant hawk-moths, 
With respect to the mode in which they undergo pupation, there 
is a slight variation, the majority descending into the earth, and 
forming an oval cell, whilst a few form a leafy cocoon on the surface 
of the ground. In their perfect state they offer no other variation in 
habits, than as connected with their more or less powerful or slug- 
gish movements, or with the crepuscular or diurnal period of their 
flight. 
The Death’s-head moth (Acherontia Atropos) is the largest 
European Lepidopterous insect, and derives its name from the sin- 
gular skull-like patch on the back of the thorax. This marking, 
together with the shrill sound which the insect emits when alarmed, 
has rendered it an object of alarm to the ignorant in seasons when 
it has abounded, as in 1826, when the most ridiculous statements 
appeared in the public prints respecting them. This noise has been 
the subject of much investigation, which must still be considered as 
unsettled. By Réaumur and Roesel it was supposed to be caused by 
the friction of the labial palpi against each other ; and by Passerini, 
that it was produced within the head, in which is a cavity connected 
with the spiral tongue (Osservazioni, &§c. Pisa, 1828; and Ann. Sez. 
Nat. vol, xiii, p. 332.; and Bull. Sci. Nat. February, 1829 ; and ditto, 
