38 
As already stated, the insects of the genus Saturnia are among the 
largest of the Nocturnal Lepidoptera, a few Hepialide and Erebi 
alone equaling them in size. How far this circumstance gives them 
the character of a typical group may be reasonably questioned ; to me 
indeed it appears that an increased size in the species of any group is 
in itself a proof of a certain degree of aberration : certainly if strength 
of flight and compactness of form be considered, we must regard the 
Lasiocampe and allies as much rather the real representatives of the 
Linnean Bombyces ; just as in the Butterflies, no one would consider 
the species of Papilio on account of their large size as the types, but 
would confer that title on Vanessa and its allies, notwithstanding the 
want of well-developed fore-legs. Another circumstance which might 
be alleged as a proof of the typicality of the Saturnia, is the wide geo- 
graphical range of the species, which occur in all quarters of the globe, 
which peculiarity extends even to the minor divisions of the genus ; 
thus we have very closely-allied tailed species from North America, 
India and South Africa; I believe however that naturalists have at 
length agreed in refusing to this circumstance the right of conferring 
typicality on groups. 
Saturnia in fact appears to me to be one of those groups like Pa- 
pilio among the Diurnal Lepidoptera, Carabus among the Carabidae, 
Feronia among the Harpalide, or Cicindela among the Cicinde- 
lide, which are of great extent and comprise a number of species, 
generally of comparatively large size, which it is difficult to group 
into well-defined sections or subgenera, although their forms are very 
varied. One or more species may be detached and characterized as 
distinct subgenera, but when the whole group is carefully studied, it 
is ascertained that these particular species do not possess more im- 
portant characters than the rest. I shall not attempt therefore, in 
describing the African species alone of this group, to introduce a system 
of distribution among the species, further than the artificial division 
given below. 
The beautiful markings of the wings, and especially of the hind- 
wings, of many of these insects, appear to indicate the character laid 
down by Linnzeus and Fabricius, namely “ Ale patule,”’ by which 
we are to understand, that when the insect is at rest the fore-wings 
do not closely cover the hind-ones, as is the case in the species with 
dingy-coloured hind-wings, but leave their beautiful markings exposed 
to view. Mr. E. Doubleday indeed informs me that the North 
American S. Luna generally sits with its wings perpendicularly ele- 
vated over its back, like a butterfly at rest. These beautiful eye-like 
markings of the wings are indeed a good character of the group, al- 
though that which is afforded by the arrangement of the veins above de- 
scribed is of higher importance. The latter indeed, together with the 
emission of four branches from each joint of the flat pennated antennz, 
may be considered as the essential characters of the genus, although 
they have never hitherto been employed to distinguish it. Another 
character, also hitherto unemployed, which will I think prove of im- 
portance in determining the minor groups of Saturnia, consists of the 
difference in the number of branches in the antennee of the different 
species ; this I have carefully noticed in the following descriptions, as 
