life-history of Pericoma canescens (Psychodidse). 147 
The legs of the fly, enclosed in their pupal sheaths, are 
short, and, though extended at full length, do not reach 
beyond the second abdominal segment. 
As in many other pupae of this and other orders, the 
abdominal segments are roughened by spines. Each 
segment bears a prominent circle of large spines and 
dense patches of smaller ones. 
The circles of hooks upon the abdominal segments of 
the pupa, serve, as in many like cases, as means of loco- 
motion. The pupa can thus place itself favourably, and 
preserve the most convenient attitude, viz., with the 
head and respiratory trumpets uppermost. Pup^e kept 
in dishes are able to creep up the steep and polished 
sides, and make their escape. When placed in water, 
they float at the surface, the respiratory trumpets break- 
ing the surface-fllm. The body is then inclined at an 
angle of less than 45° with the surface of the water, and 
the orifices of the respiratory trumpets being obliquely 
truncated, lie in the surface-plane. The abdomen is 
flexed and extended at intervals, and can also be bent a 
little to either side. 
We have found it so laborious and yet so necessary, 
when dealing with the life-history of any insect, to refer 
to the writings of earlier naturalists who have described 
the same or nearly allied species, that we gladly present 
as an Appendix, the following Bibliography of Psycho- 
didse (early stages), with critical remarks, which we owe 
to the great kindness of Baron Osten Sacken : — 
APPENDIX. 
I. — LlTERATUEE OP THE EaELY StAGES OF PsYCHODIDiE. 
(In chronological order.) 
1. ScHRANK, F. p., Beitr. z. Naturgesch., 1776. In 
my manuscript notes I find this article connected with 
Pericoma ocellaris, Meig., the pupa of which is said to 
be figured in it. I do not remember where I found this 
reference, and cannot verify it now. It may be the same 
as Schrank, No. 2, in Hagen^s Bibliotheca ; Beschreibung 
einer Miicke. {Tipula, with fig.) 
2. BoucHE, Naturg., etc. (1834), p. 28, Tab. ii., 
figs. 20-23. Psychoda jplialsenoides , Meig., i., p. 104. 
Bouche adds the reference : Tip. pliaJsenoides, Linn. 
But according to the present nomenclature by Haliday 
