oe GILBERT C. BOURNE. 
separated from the chitinous shield of the cephalothorax, and 
forms a relatively thin cord traversing the latter. 
Claparéde pointed out that the males differ from the females 
in this respect: they have, in fact, powerful longitudinal mus- 
cles in the cephalothorax, which are not figured by Claparéde ; 
their arrangement is shown in fig. 5. In the female the 
ripe ovary distends the body and causes it to fill the cephalo- 
thoracic shield completely. It is in the form of a single 
median sac, and extends when full nearly as far forward as the 
eyes. The ova are relatively large and filled with yolk-sphe- 
rules. Semper’s specimen, which he describes as having very 
small ova, with the ovary extending very little into the cepha- 
lothorax, was probably unripe. The oviducts are difficult to 
distinguish, as they are compietely hidden in the anterior part 
of the thorax by the muscles. Their terminal portion is easily 
distinguishable in a side view, but not from above or below for 
the same reason. As far asI have been able to make out, the 
two oviducts are united shortly before their termination, and 
open by a common pore on the ventral surface of the first 
abdominal segment between the origins of the genital sete. 
The testis does not appear to offer any peculiar feature, as 
compared with that of other Copepods. 
The nervous system has been described by Semper and 
Claparéde. I was able to follow its general character in 
sections. It consists of a large cerebral ganglion, with which, 
judging from the position of the cesophageal cord, several post- 
oral ganglia are fused. Nerves are given off from the cerebral 
ganglion to the antenne, and to the antennary muscles. The 
optic nerves can be distinguished in sections as short stems 
rising from the upper and anterior part of the ganglion. 
Posteriorly the ganglion is continued into the ventral cords, 
which appear single in a surface view, but are shown to be 
double in section. This double cord traverses the elongated 
anterior segment, and just before the origin of the first pair of 
swimming feet enlarges into a ganglion, from which stout 
nerves are given off to the swimming feet and to the longitu- 
dinal muscles of the body. From this point the ventral nerve- 
