610 
POPULAE SCIENCE EEVIEW. 
ganglion^ which again is succeeded by the third and fourth, 
making four in the second segment. A single ganglion, the 
fifth, exists in the third segment, the sixth in the fourth, and 
so on till the ninth segment, in which we have both the eleventh 
and twelfth situated. These two ganglia are seen in fig. 2. 
All the sub-intestinal ganglia but the first and last resemble 
the eleventh in their form and structure, and in the manner of 
the origin of the nervous twigs. Those of the second segment 
are, however, much larger than the others. The commissm^es 
which connect the several ganglia consist f of two cords of 
nerve fibre, which for the greater part are fused together. No 
large branches are given ofi* from the commissures, excepting 
between the first and second ganglia, where two large twigs 
arise, supplying apparently the muscles of the jaws. The dis- 
tribution of the branches from an ordinary ganglion is as 
follows. The branches marked a (fig. 2), supply the more 
superficial muscles ; those marked h, are distributed to the 
deep muscles ; and those marked c, are connected with gangli- 
onic enlargements at the bases of the httle hairs (fig. 10) with 
which the surface of the body is supplied. 
Organs of sense . — The only organ of special sense which the 
larva possesses is the eye. A pair of compound eyes and a 
rudimentary simple eye placed near it are situated one on 
either side (fig. 1, /), just below the cephalic ganglion [h), 
and near the mouth and jaws. * The eye consists of a great 
number of minute lenses arranged in connection with a mass 
of pigment so as to affect the nerves connected with the 
cephalic ganglion. An enlarged view of one of the compound 
eyes is given in fig. 4. The rudimentary eye, noticed by 
Leydig in his paper, is merely a small mass of pigment placed 
by the side of the compound eye, and not provided, as far as 
we could ascertain, with anything like a lens. 
Regjroductive Organs . — In the eighth segment are two 
cellular bodies of an elongated elliptical shape. Dr. Leydig 
considered these as rudimentary reproductive organs, an 
opinion in which we are inclined to coincide (fig. 1, n). 
We trust that the foregoing remarks on the anatomy of this 
pretty little creature may have proved of some value to the 
reader, and that they may assist him in working out on some 
future occasion the history of the larva of Coretlira gjlumicornis. 
EXPLANATION OF PLATE. 
Fig. 1. Larva of Oorethra plumicornis (natural size two-thirds of an inch). 
a. Oar-lihe appendages, or Tarsognaths. 
h. Labial bristles, or Trichoffiiaths. 
