92 ZOOLOGY. 
Cxass III.—CrenopHora (Comb-bearers). 
General Characters of Ctenophores.—These beautiful an- 
imals derive their name Ctenophora, or ‘‘ comb-bearers,”’ 
from the vertical rows of comb-like paddles (ctenophores) 
situated on meridional bands of muscles which serve as lo- 
comotive organs, the body not contracting and dilating as 
in the true jelly-fishes. In their organization they are 
more complicated than the Actinozoa, as they have a true 
digestive cavity passing through the body-cavity, with two 
posterior outlets (it will be remembered 
that’ Cerianthus has one at the end of 
the body). From this alimentary canal 
are sent off chymiferous or water-vascn- 
lar canals (Fig. 61) which correspond in 
their mode of origin with the water- 
tubes of the Echinoderms. As regards 
the rows of paddles, each vertical row 
consists of a great number of isolated, 
transverse, comb-like fringes placed one 
above the other, and movable, either 
isolately or in regular succession or 
simultaneously (Agassiz). As these rows 
of paddles are connected for their whole 
Iie. Pigeon of the length with a chymiferous tube, they 
aetro-vascular canals of a probably aid in respiration, These ani- 
the two retractile arms mals also stand much higher in the scale 
have b removed. > : 
from one side, the mouth. of life than the other Celenterates by 
Peenine ae veiend = ~being more truly bilateral, the radial 
Sean oes symmetry so marked in the Actinia or 
in the jelly-fish being in these animals less apparent, as the 
parts are developed on opposite sides of a median plane. 
The nervous system, as originally described by Grant, con- 
sists of a ganglion situated at the aboral end (end opposite 
to the mouth) of the Pleurebrachia, from which, among 
other nerves, eight principal ones are distributed to the 
eight rows of paddles. A nerve also proceeds to the so- 
called otolitic sac (lithocyst) seated upon the ganglion. 
Eimer has lately shown that the nervous system of the 
