PSYCHE. 
the mandibles have their insertion on the 
exterior proximal angle of each mandible 
and their origin on the chitin supports a 
and 6. The broadly pinniform flexor mus- 
cles of the mandibles have their insertion 
on the interior proximal angle of each 
mandible, and their origin on the chitinous 
supports @ and m and on those which pass 
anteriorly and posteriorly from the support 
e; they thus le dorsally and the extensors 
ventrally. The mandibles are directed ex- 
actly anteriorly, in the axis of the body ; 
and not ventrally. 
The maxillae (fig. 2 and 3, 7) and the 
labium (fig. 3, v) in the early form are 
attached to a common protrusile basis, the 
limits of which are partly indicated at -g 
(fig.2). The maxillae are very rudiment- 
ary, but that they are maxillae is shown 
by their being cleft, for if they were labial 
palpi they would not be cleft, but would 
probably be jointed. Further, as nearly as 
could be determined from a number of lar- 
vae found in the act of molting, at the time 
when they pass from the earlier to the later 
form, the maxillae of the later form were 
drawn from the skins of these cleft appen- 
dages. In still further support of the view 
that these mouth-parts are maxillae is their 
position, which is with their apical extrem- 
ities slightly above the level of the labium, 
as can easily be seen by careful focusing 
with a high-power objective. The max- 
illae of the early form, then, are only lat- 
eral, outwardly-curved processes, each side 
of, and attached to the same support as the 
labium. 
The labium of the early form (fig. 3, v) 
is bilobed, with a few delicate grooves and 
thickenings, and is covered distally with a 
rasp of fine spines. It can be protruded, 
101 
together with the maxillae, beyond the ex- 
tremities of the mandibles, and has a slight 
lateral motion. No traces of a spinneret 
are visible in the early form of larvae. 
The support common to the maxillae 
and labium consists of two chitinous rods 
(fig. 2, 7) passing posteriorly, diverging 
slightly, and then suddenly curving in- 
ward. The support is retracted by a mus- 
cle between the posterior ends of these 
chitinous rods (fig. 2, 4) and a part (fig. 
2, 9) of the ring at the posterior portion 
of the head. I was unable to discover 
Fig. 3. — Comparison of the separated mouth- 
parts of the early and later larval stages of Gra- 
cilaria syringella : v, v’, labium of each form; t, 
labial palpus of later form. 
any opposing muscle, and I think the labio- _ 
maxillary support is protruded by the ac- 
tion of the fluids of the head. 
After the molting by which the larva 
enters upon its later or more cylindrical 
stages, the head becomes broader and 
thicker in proportion to its length, a few 
hairs appear on its .anterior portions, the 
mouth-parts are directed a little ventrally 
from the axis of the body (fig. 4), and the 
condition of the trophi and their supports 
is as follows : — 
The chitinous supports of the parts of 
the head are somewhat modified from what 
