Noland—Anatomy of Troctes Divinatorius Muell. 
203 
d.b.) whose function was not determined. The vasa deferentia, 
which are long, slender, transparent tubes, lead by a somewhat 
winding course to the seminal vesicles, entering them laterally just 
anterior to their union in the ejaculatory duct. 
The copulatory apparatus through which the ejaculatory duct 
passes is a complicated chitinous structure, the anterior end of 
which makes an acute angle; while the posterior part terminates in 
a pair of hooks which curve in toward each other and close about 
the end of the ejaculatory duct. When drawn well into the body, 
as figured, the anterior tip of the structure reaches as far anteriorly 
as the posterior ends of the seminal vesicles, but the apparatus can 
be thrust out of the abdomen to nearly one-half of its total length. 
This copulatory apparatus consists of three pairs of chitinous 
plates (fig. 13, prs. 1, 2, 3). The inner pair (fig. 13, pr. 1), broad 
and flat and slightly curved at the posterior ends, is in contact with 
the ejaculatory duct and forms the foundation to which the other 
two pairs are attached. The acute angle of the apparatus is 
formed by the second pair (fig. 13, pr. 2) which is more heavily 
chitinized and slender than the others and comes in contact with 
pair one at the anterior ends of the latter, ending there. The third 
pair (fig. 13, pr. 3) is heavy, like the first, and is attached to both 
of the other pairs, uniting with the first pair at its posterior end 
and forming there the outer portions of the terminal hooks (fig. 
13, t.h.). The anterior parts of the third or outer pair unite with 
the second pair at about their middle. Thus the third pair vir¬ 
tually forms both a sheath for the posterior parts of the other two, 
and the posterior hooks or ‘‘forcepsthemselves. 
The Nervous System 
The central nervous system of Troctes is of a simple type, com¬ 
posed of the supraoesophageal ganglion or brain (fig. 15, s.g.), the 
suboesophageal ganglion (fig. 15, sb.g.), and three thoracic ganglia 
(fig. 15, g.l, 2, 3). The last two thoracic ganglia are fused into a 
large mass which appears externally to be but one, though in sec¬ 
tion its compound nature is revealed. The length of this last 
ganglion and a slight constriction at its posterior end makes it 
appear as if a third ganglion, originally abdominal, may have 
taken part in its formation. This ganglion sends out a nerve, or 
group of nerves (fig. 15, n.) as a prolongation from its posterior 
