606 
POPULAE SCIENCE EEVIEW. 
it^ however^ gives support to four hairs in each segment of 
very beautiful structure (fig. ’lO). This hyaline skin is shed 
several times in the course of the larva^s existence until it 
becomes a pupa. It is underlain by a tunic of granular tissue 
containing cells^ which are very well seen in one of the 
terminal plates (fig. 6). The parts about the head are not soft 
like the rest of the body_, but have a yellowish appearance, 
and are chitinous — there are also two chitinous hook-like 
bodies and twelve small serrated plates at the other extremity 
of the body (fig. 1, s). 
Organs of prehension and mastication. — The anterior portion 
of the body is terminated by two remarkable-looking arms 
(fig. 1, a). Each consists of two parts, a stem and four long 
terminal bristles ; the base of the stem is hollowed out and in- 
serted into the head, where it is connected with a long muscle, 
which can easily be seen running beneath the transparent 
skin (fig. 1, e). These organs move by very sharp jerks, and 
seem to aid locomotion as well as the capture of prey. Suc- 
ceeding these arm-like bodies is a group of ten long and thick 
hairs, which are all connected with a muscle at their base (fig. 
1, &), Next to these come two very curious saw-hke little 
bodies (fig. 1, c; fig. 11), which appear to be quite immovable. 
Behind these, in the central line, is a projecting cylindrical 
body, which is moved either backwards or forwards by two 
muscles which may be very readily observed. The top of this 
organ is covered by two groups of hairs, which are arranged 
so as to point towards the mouth. Then follows the mouth, 
which is armed on either side by two very powerful jaws, whose 
form and arrangement will be best seen in the figure (fig. 1, g). 
The chitinous material of which the jaws are formed spreads 
over a large portion of the head, and forms a protecting shield 
to some delicate organs placed beneath it. On the inner 
surface of each jaw is a group of twelve hard bristles, which 
are closely packed together, and have one edge very finely ser- 
rated. They doubtless act like the jaws in crushing and 
breaking up the smaller animalcules {entomostraca, &c.) on 
which the Corethra larva feeds.* 
Organs of digestion. — The pharynx, commencing from the 
mouth, is very muscular, and expands in the second segment of 
the body into a large sac (fig. l,j) (fig. 6) ; it terminates in the 
second segment in a rounded muscular body, which is of a 
bright yellow colour. The muscular fibres in the walls of this 
little gizzard are arranged horizontally and laterally also, and 
appear to give it very great power. Extending from this 
These bodies may be conveniently denominated, successively, Tarsognaths, 
Trichognaths, Pristognaths, Mesognaths, Platygnaths, and Charactognaths. , 
