476 
ZOOLOGICAL LITERATURE. 
when progression depends on limbs with rotatory coxse, he 
names the animals Trochalopoda. 
The ordinary distinction between the Heteroptera and Ho- 
mopteray according to which in the former the rostrum springs 
from the front of the head {Frontirostrici) y and in the latter 
from the immediate neighbourhood of the prosternum [Gulce- 
rostria)y is shown by the author to be inadmissible, as the two 
forms graduate insensibly into each other. He indicates, as a 
broad line of demarcation between these two great natural 
groups, that in the 
Homoptera the first pair of coxse artieulate with the cheeks, 
whilst in the 
Heteroptera the cheeks and first pair of coxse do not touch each 
other. 
He finds a perfect concurrence between these peculiarities 
and the habits of the animals belonging to the respective groups. 
Thus all Homoptera are phytophagous ; ' hence their general 
thickset form, the small amount of movement possessed by the 
head, and their Pagiopodous structure. Of the Heteroptera 
some are carnivorous, whilst others live on a mixed diet ; and 
accordingly as the diet is more of a vegetable nature, so do the 
animals approximate to the Homopterous type of structure, and 
become Pagiopoda. Of the Trochalopodous Heteroptera some 
live on mixed food, and exhibit a characteristically expanded 
form of body ; others are purely carnivorous, and are of a slen- 
derer form. The parasitic Rhynchota, which possess a tele- 
scopic rostrum, are pagiopodous; the author regards them as 
forming a distinct section [Biphunculata) of equal value with 
Heteroptera and Homoptera. 
After discussing the disputed question of the number and 
position of the spiracles in the Rhynchota, and the structure of 
the odoriferous glands and their orifices, the author gives the 
following sketch of a classification of the Rhynchota in accord- 
ance with the principles laid down in his memoir. Its most 
striking peculiarity is the removal of the Nepce to a distance 
from the other Water-bugs. The author^s arguments in favour 
of this change are too detailed to be given here. 
Table of the Families of Rhynchota. 
I. Gense excavatae, coxas primas excipientes. 
[Coxse posticse cardinatse, scrobiculis femoralibus instructse.] 
Subordo Homoptera. 
II. Gense integrse, a coxis remotae. 
Subordo Heteroptera. 
A. Coxae posticae acetabulatae, rotatoriae, scrobiculis ferao- 
ralibus nullie : Trochalopoda. 
