” 
Life-history of Phalacrocera replicata. 547 
a patch of scales in the same position; all the annuli 
except the first have a pair of lateral ventral processes, 
which increase in length and become more widely sepa- 
rated from the 2nd to the 5th annulus. The last or 
ilth segment has no ventral processes, except a median 
setose tubercle on the second of the two annuli which le 
in front of the anus. 
These large and numerous processes suggest a respira- 
tory function, which is partly confirmed by the presence 
of a good-sized trachea, running along every one. Inthe 
branched processes there are, as De Geer remarks, two 
separate trachez, which diverge at the fork. 
Sections through the processes show that they are 
covered by a cuticle of relatively enormous thickness, far 
exceeding the diameter of the contained trachee ; it is 
dense and tuberculate externally, but less compact 
within, the generating epidermis coming nearly into con- 
tact with the generating layer of the trachea (fig.31). So 
thick and solid a covering is not easily reconciled with the 
respiratory character of the processes. It will be seen 
from the description of the tracheal system that the larva 
has spiracles, and that it visits the surface occasionally to 
supply them with air. 
The closest parailels that we know to the numerous and 
long appendages of this larva are found, not in any 
Dipterous larva, but in the Lepidopterous Paraponyx 
stratiotata* and the Coleopterous Cnemidotus cxsus.t 
Trichopterous larvee too may bear filaments more or less 
like those of Phalacrocera.t 
The larva has no true limbs. The last segment bears 
a pair of large, curved anal hooks, which are strongly 
chitinised on the convex dorsal side (figs. 1, 2,4). Near the 
base and on the concave side is a setose tubercle. ‘he 
tip of the hook is bifurcate, and just beneath it is a small 
bunch of setz. ‘These hooks are constantly used for 
grappling and locomotion. ‘The “small anal hooks’ of 
De Geer are described in connection with the dorsal 
processes (p. 346). 
* De Geer op: cit.,.1., pl. dv. 
+ Schiddte, De met. Eleutheratorum. 
~ The insects quoted are all aquatic. The terrestrial larva of 
Cylindrotoma (p. 351) bears similar but sherter processes. 
