HYDllOZOA. 



05 



to the exterior ou each side of a eentnilly-i»lact'cl " amlitory " or 

 bahiiiciu<i; sense-organ. 



Some Ctenophorans are provided witli a pair of phimose teuiaeles, 

 which can be retracted into receptacles. Honnipltora plumomi • 

 (Fig. 20) has a small peiir-shaped ])i)dy, the mouth Ijeing at the 

 narrow end : the eight rows of swiinmimr-plat -s ueeiipy aljout two- 

 thirds of the length of the boily ; a pair i)f luiig feathery teutaclen 

 can be emitted from two tentacle-sheaths, which open one ou each 

 side of the body not far fi'oin the :il)oral pole. 



Gestus reneris, or "Venus' (Jirdle" * (Fig, 27), has a long l)and- 

 sliaped body, which may attain a length of several feet ; the mi>utli 

 is in the centre of the lower l)()rder, and the gullet and st<»iiiacli 

 occupy quite a narrow area in the centre of the band ; the eiirht 



Vic. 27. 



I' 



rrttk t 



B 



Ce%tm veneris, a, adult, b, younjj. mth, inoutli ; /. teiitucles ; //. liitiml 

 tentacles ; spV. one of the tour short rows of swimming plates ; xiil', 'Hi.- 

 of the four long rows of swimming plates. (After Chun ; from Parkir 

 and Haswell's Zoology.) 



rows of swimming-plates form an apparently continuous line ou each 

 edge of the upper border. The young ( 'est us is spheroidal. Itut soon 

 Ijecomes compressed in a vertical i)laue and lengthened out. 



Cesttfs swims mainly by the wavy and serpentine motion of its 

 body. The small exhibited specimen shows the aboral border, with 

 its apparently continuous rows of swimming-plates nearest the front 



of the glass. 



Bf'ioe omta* from Naples is in the form of a large sju- with a 

 wide mouth ; the cavity of the sac is, strictly speaking, the gullet, 

 the stomach occupying only a small space at the base, 



JJeroi'- orata can alter its shape to a remarkable extent while 

 swimming, being now V-shaped with widely-gaping lips, now 

 U-shaped ; tiie crealure is extremely vorai-ious. and can tak.- into il,s 



