248 THE OCEAN WORLD. 
the coral polyp, which have a central, perhaps a sensible organ, 
common to all, which binds them to each other, giving a certain 
unity to their acts. The Gorgonian polyps have no will; the Pen- 
natula have.” 
CTENOPHORA. 
We have now reached the class of polyps which Cuvier designates 
Hydrostatic Acalephe,and which De Blainville calls the Ci/iobranchiata. 
The body of these polyps presents marginal fringes furnished with 
vibratile cilia, which: are swimming organs. Moreover, as these 
vibratile fringes are inserted directly over the principal canal, in 
which the nourishing fluid circulates, they ought necessarily to help 
in the act of respiration, by determining the renewal of the water in 
contact with the corresponding portion of the tegumentary mem- 
brane. 
The class may be divided into five families, namely, Cal/ymmide, 
Cestide, Callianiride, Pleurobrachiade, and Bervide. 
The creatures belonging to these families swarm in the deep 
sea; they often appear quite suddenly, and in vast numbers, in 
certain localities. 
Berbe Forskalit (Fig. 102), has been studied with great care by 
M. Milne-Edwards. The species inhabits the Gulf of Naples, and 
the sea almost everywhere; the sailors of Provence call them Sea- 
cucumbers. The body (Fig. 102), cylindrical in form, is of a pale 
rose colour, thickly studded with small reddish spots, so numerous 
as to appear entirely punctured with them. It presents eight blue 
sides, with very fine vibratile cilia, which by their reflection produce 
all the colours of the rainbow. The substance of the body is 
gelatinous, its appearance glass-like; its form varies according as 
the animal is in motion or repose. Sometimes it swells up like a 
ball; sometimes it reverses itself, so as to resemble a bell; at others 
“it 1s ‘elongated and cylindrical; at its lower extremity it ‘presents a 
large mouth ; at its upper extremity is found a small nipple, having 
at its base a spherical point of a reddish colour, enclosing many 
crystalloid corpuscles, which rest upon a sort of nervous ganglion, 
whose physiological function is not very well determined. A vast 
stomach, considering its size, occupies the whole interior of the body 
of the Bere: the circulation is also much developed in this creature. 
The circulating apparatus contains a moving fluid charged with a 
multitude of circular, colourless globules, which flows from a vascular 
ring round the mouth towards the summit of the body; in the 
interior are eight superficial canals, which flow under the ciliated 
