132 
C@LENTERATA. 
Externally, Cydippe is bi-plano-symmetric, for the plane passing 
through the tentacles and their sheaths, called the coronal plane, differs 
from that perpendicular to it, or the sagittal plane. Both planes, however, 
divide the animal into symmetric halves. The gullet is flattened and 
Fig. 66.—ABORAL VIEW OF CyDIPPE. (After CHUN.) 
Aboral Sense-organ. 
Horizontal Canals. 
Tentacle. 
Longitudinal 
Nerve. 
elongated in the sagittal plane, as in Activa. Each of these planes 
corresponds to two opposite per-radii. The stomach gives off, near the 
gullet, four inter-radial canals which run horizontally outwards, each 
Fig. 67.—ADHESIVE CELLS OF 
CypIpre. (After HERTWIG.) 
Highly Magnified. 
Head. 
Stalk. 
5S 
= 
< 
bifurcating into two ad-radials. Each 
of these joins a long meridional canal 
running from oral to aboral end just 
below each row of the combs. 
The aboral sense-organ consists of 
a ciliated depression containing small 
otoliths (cf Obelia) and probably 
governs the equilibrium of. the ani- 
mal. From it there pass eight 
nerves down the eight rows of combs. 
The ccelenteron is here partially 
divided, as in Actinza, into a central 
gastric cavity or stomach and peri- 
pheral nutritive, or vascular cavities. 
The muscles are not represented, but 
the gonads (Cydifge is hermaphro- 
dite) are situated on the walls of the 
meridional canals. The mesoglcea is 
enormously developed and forms the 
main bulk of the organism, filling the 
space between ectoderm and endo- 
derm. Nematocysts are not found in Cydipfe but they have been 
described in some members of the group. 
