170 
Fannia caniciilaris etc. 
(as shown in Fig. 7) but much less pinnate and shorter than the latero- 
dorsal series. The latero-ventral processes of segment XII are situated 
more ventrally than those of the preceding segments and their usual 
place is taken by a small group of spines. Posterior to the base of each 
of the latero-dorsal processes of segments V to XI is a small branched 
process. 
On the ventral side of the larva, extending from segments IV to XI, 
there is a series of pairs of small spiniferous papillae, as shown in Fig. 7, 
each of which is situated at the end of a transverse row of spines. 
Posterior to this transverse row of spines there is a shorter row of spines, 
divided into four groups. The anterior, or prothoracic, spiracular pro¬ 
cesses are six to eight-lobed; the usual number of the lobes being 
seven. The posterior spiracular processes are very similar to those of 
F. canicularis. Vogler (1900), who has given a good description of this 
larva, illustrates the anterior spiracular processes with eight lobes, and 
his figure of one of the posterior spiracular processes is not very clear. 
The feathery character of the processes of F. scalaris is probably 
associated with the fact that the larvae usually live in substances of 
a semi-liquid character where such processes will be more advantageous 
than those of F. canictdaris for -life in such a medium. It may be of 
interest to note in this connection that the spiniferous and branched 
lateral appendages of the larvae of the genus Fannia were considered 
by Walsh (1870), and probably by other entomologists, to be ‘ branchiae’ 
or gills. Walsh (l.c.) stated: “The larvae...wallow in moist decaying 
matter, whether animal or vegetable; and as in such situations they 
would be sometimes stifled for want of air, if they breathed through 
the spiracles or breathing holes with which all air-breathing insects 
are supplied, nature has replaced the spiracles by lateral ‘branchiae,’ 
or gills, by means of which they are able, after the manner of a fish, to 
extract the air from the fluids around them,” and he compares them to 
the gills of the Ephemerid larvae. 
Prior to pupation the larva leaves the moist situation for one of 
a drier character and the pupation is similar to that of F. canicularis. 
F. scalaris is more commonly found than F. canicularis as the cause 
of intestinal myiasis and it also breeds more commonly in human 
excrement. These facts make its economic relation to man one of not 
a little importance. 
