a new J arm of larvse of Pf^ychodidfe. 491 
Ps. 4), but more robust. Yet it is difficult, under the 
hypothesis advanced, to explain everything in the 
interior parts of the figure — what that is, for example, 
into which the apical joints of the supposed superior 
appendages are clenched. If they overlaid instead of 
underlying the hues that cross them in the figure, 
things would be more intelligible ; and, therefore, it is 
quite possible that the perspective of these details in 
the original drawing was at fault. A figure of such 
intricacy as fig. 19 can rarely be elaborated symmetri- 
cally directly from the specimen, with true regard to 
effect, owing to the parts being not all in one plane, and 
owing to the consequent optical distortion produced by 
the necessary shifting of focus during the progress of 
the work; and when obliged to have recourse to 
duplicated tracings for the composition of a figure, or 
to combined tracings of detached details, the most 
skilful professional artists often experience great difficulty 
in bringing all the parts into their proper bearings, and 
are liable to fail in achieving this without advice from a 
specialist in the same class of subjects. 
The attitude of the living fiy in repose (fig. 11) and 
Dr. Miiller's remarks about it, quite bears out the 
supposition that M. pilosella may be a Psychoda : species 
related to Ps. phal^noides adopt the same attitude, or 
almost exactly the same, during life — the antennae 
divergent slightly forwards from the prone head, and 
the wings almost vertically deflexed alongside of the 
legs. In death, or wh%n they " sham dead,^"* the antenna 
in these species are thrown back beside the legs below 
the deflexed wings. But some of the other species {e.g., 
Ps. Jmmeralis) assume this posture only when dead or 
shamming death ; during life they have the gait of a 
Pericoma, carrying the wings sub-horizontally divergent 
from the fold of deflection. 
In specimens that have died with the wiogs deflexed 
(occasionally some die with them erect), it is often 
difficult to get rid of the twist in the wing and force it 
to lie out flat enough for the tracing of neuration to be 
accomplished with exactitude. Dr. Midler, judging from 
fig. 12, seems to have encountered this difficulty : the 
wing-membrane is represented as cockled up in parts, 
and the nervures partly out of focus. If the figure be 
compared with the figures of wings of P«? alhipennis 
