perfect State of Prosopistoma punctifrons. 79 
The facies of Prosopistoma punctifrons in this state (fig. 7) re- 
sembles that of Canis ; its body is a little shorter in proportion 
to its breadth, which gives the animal, when its wings are 
extended, a certain vague resemblance to some Diptera. 
The general colour of the integuments of the subimago is 
reddish brown, darker on the dorsal than on the ventral 
surface, where the tint even becomes very light at certain 
points (at the insertions of the legs); the wings are of a pretty 
dark iron-grey, especially the first pair. 
The coalescence of the ditferent regions of the body no 
longer exists in so marked a manner in the perfect state ; on 
the contrary they are very distinct. I now proceed to give 
a detailed description of each of them, and to show the import- 
ance of the modifications superinduced by the metamorphosis. 
The head is slightly triangular in form. When seen from 
above, it shows in the middle an inflated part bounded in 
front and on the sides by a sinuous line. In front of this line 
is the median ocellus, which forms a slight projection beyond 
it; on each side of this we observe the antenne, the points of 
insertion of which are rather on the ventral than on the dorsal 
surface; behind we see the lateral ocelli placed on each side 
of the cephalic prominence, at the points where the sinuous 
line already mentioned: becomes confounded with the integu- 
ments. The compound eyes occupy quite the lateral parts of 
the base of the head (figs. 7, 8) ; in consequence of their posi- 
tion, they are equally visible whether the animal is viewed 
from the upper or the lower surface. 
The ventral or inferior surface of this first region of the body 
(fig. 8) shows in front the points of insertion of the antenne ; 
the ‘median ocellus, which, as just stated, is placed between 
these organs, is more or less distinct according to the inclina- 
tion given to the body of the animal; further back there is a 
strongly marked line bounding the clypeus, which, in conse- 
quence of a special modification, terminates rather low down 
on the ventral surface. It is in the interior of the concavity 
formed by the margins of the clypeus that all the buccal organs 
are placed. ‘The large dabiwm, which led to the name of Proso- 
pistoma being given to the nymphal state, from its resemblance 
in this species to a mask (see fig. 4), has become completely 
atrophied, and leaves exposed the rudiments of the maaille 
and mandibles ; of all the buccal organs the labrum is the only 
one that has retained a well-defined form. 
In the dorsal view of the animal (fig. 7) the thoracic region 
presents an exceedingly short prothorax, the anterior margin of 
which is slightly convex in the middle, while the posterior 
margin is alittle concave. ‘Then follow the mesothorax and the 
