and Classification of Rhynchota. 229 
gists evidently thought that they might content themselves 
with treating the matter from the point of view of simple 
horismology, and that, at any rate, the distinction practically 
worked so well that a morphologically true character might 
be dispensed with, just as ichthyologists are content to say 
that the mouth in Sturgeons and Plagiostomata is placed on the 
under surface of the head. But the fact is that the definition 
does not hold good even if it is understood in a purely horis- 
mological sense—that is, even if the parts are named without 
regard to their morphological value. Between the structure 
of the Reduvii, where the rostrum appears as an immediate 
continuation of the top of the head, and that of Cicada, where 
it closely adjoins the prosternum, there is a series of insensible 
transitions, represented by the swimming species, as well as 
by many living on the land, such as the Platycephala; and 
. the whole question about the so-called position of the rostrum 
resolves itself into this, that the forehead is more or less bent 
in under the head. The distinction hitherto supposed to be 
expressed in the position of the rostrum is as untenable as 
that derived from the wings; and the diagnoses of the two 
suborders have become so loose and indefinite, and, by addi- 
tional explanations and restrictions so prolix, that, in the 
new manual of Fieber on the European Rhynchota-fauna (a 
volume in large octavo), they fill respectively nine and sixteen 
closely printed lines in small type. ‘There is evidently here a 
serious defect in our knowledge. Unless a clear and well- 
defined mark of distinction between the two suborders can be 
found which is connected with their mode of life and expresses 
