512 C. GORDON HEWITT. 
the position of the pharyngeal skeleton, to the whole of which 
the name “‘ cephalo-pharyngeal skeleton’ has been given. All 
that now is left of the cephalic segment consists of a pair of 
oral lobes, whose homology with the maxille is very proble- — 
matical, and at present is not safely tenable. On the dorsal 
side the oral lobes are united posteriorly. Hach bears two 
conical sensory tubercles (0. t.), which are situated, the one 
dorsally, and the other anterior to this and almost at the apex 
of the oral lobe. The ventral and ventro-lateral surfaces of 
the oral lobes are traversed by a number of channels, which 
will be described later. 
The post-cephalic segment, which is composed of the first 
and second post-oral segments and represents the second and 
third segments of the body, is conical in shape. The first 
post-oral segment (ii), to which Lowne gave the name 
“Newport’s segment,” is limited posteriorly by a definite 
constriction and is covered with minute spines. The second 
post-oral segment bears laterally at its posterior border the 
anterior spiracular processes (a. sp.) The remaining seg- 
ments of the body—four to twelve—are on the whole similar 
in shape. At the anterior edge of the ventral side of each of 
the sixth to twelfth body-segments there is a crescentic pad 
(fig. 5, sp.) bearing minute and recurved spines; these are 
locomotory pads by means of which the larva moves forwards 
and backwards. It is important to note that these pads are 
situated on the anterior border of the ventral side of each 
seement as they do not appear to have been carefully placed 
in the previous figures of this species. In addition to these 
spiniferous pads there are two additional pads of a similar 
nature, one on the posterior border of the ventral side of the 
twelfth body-segment, and the other posterior to the anus. 
The terminal or thirteenth body-segment is obliquely trun- 
cate, but the truncate surface, which occupies more than half 
the posterior end of the larva, is not very concave as in the 
blow-fly larva. It bears in the centre the two posterior 
spiracles (fig. 8, p. sp.), which are described in detail with the 
tracheal system. On the ventral side of the terminal segment 
