Relationships existing amongst Natural Objects. 417 
supposition that he observes, “ Habitat in Georgiæ forsan aquaticis ?” He how- 
ever noticed several circumstances which seemed to indicate an approximation 
towards Lebia, Dromius, Tarus, &.; and Dejean, without being aware at the 
time of the observations of Mr. Kirby, placed it in the subfamily Truncati- 
pennes (Brachinidæ, MacL.), with some of the genera of which group, such 
as Coptodera, Orthogonius, Thyreopterus, &c. these insects seem to me to be 
most nearly allied. 
It is certainly a curious fact in the geographical distribution of Insects, that 
so aberrant a form as is indicated by the four insects noticed above should be 
found in regions so distant as North America, Brazil, and New South Wales. 
This fact alone I should imagine must be considered sufficient to prove that a 
wide geographical range is not the character of a typical group, as stated by 
Mr. Swainson. 
The two insects represented in the accompanying figures 5 and 6, are Rhy- 
zopertha, (Steph. ) pusilla (Fabr.), and Tomicus (Latr.) fuscus (Marsh.), which 
in their xylophagous habits, cylindrical form, pitchy-ferruginous colour, punc- 
tated surface, transversely rugose thorax extending over the concealed head, 
dentate tibiæ, and short antennæ, are so very nearly alike, that by many au- 
thors they have been even placed in the same genus. A minute investigation 
of their structure proves them however to be totally different in their essential 
organs, the antennæ, trophi and tarsi. In these respects Tomicus will be found 
to belong to the group having the elm-destroying Scolytus as its type; whilst 
Rhyzopertha is most nearly allied to the genus Bostrichus of Geoffroy (Der- 
mestes capucinus, Linn.). These two groups have indeed by many persons 
been considered to belong to the same family Bostrichidæ ; and even by those 
who have ventured to place them in different groups, they have been made to 
follow each other without any intervening link ; being indeed employed when 
thus connected to form the transition between the Pentamerous Ptinide and 
the Pseudotetramerous Curculionide, to which last Scolytus most intimately 
approaches. 
That the relation between these two groups, notwithstanding the many 
points of connexion, in habit, economy, and even structure, is not an affinity, 
but merely an analogy, I entertain very little doubt, but our comparative 
ignorance of the structure and larve of the Xylophagous insects of Latreille 
312 
