PHYLUM CCELENTERATA 



223 



of these characteristic ccelenterate organs of offence that the adhesive cells of 

 Ctenophora were evolved. 



The Lobata, for instance Deiojiea, are distinguished, as their name implies, 

 by the presence of a pair of large lappets (Fig. 109 A, ///.), into which the oral 



TitnLc 



FIG. 1V.>. Deiopea kaloknenota. A, adult ; B, young, avr. auricle ; lp. lappet ; L t. lateral 

 tentacles ; mrd. c. meridional canal ; mth. mouth. (After Chun.) 



surface is produced at either end of the vertical plane. Four of the swimming 

 plates are shorter than the others, and at their bases arise elongated processes 

 called auricle* (ar.), which bear swimming-plates. The meridional canals (mdr.c) 

 unite with one another, and, with the cesophageal canals, are continued into the 

 lappets, where they become curiously coiled. The principal tentacles are 

 usually absent in the adult, but are represented by their basal portions, which 

 are small, situated at the oral end, and devoid of sheaths. From each tentacle- 

 base grooves are continued along the oral surface to the auricles, and from the 

 grooves depend numerous small lateral tentacles (l.t.). In the young condition 

 the Lobata resemble such compressed Cydippida as Euchlora, having a pair of 

 long principal tentacles, no lappets, and unbranched vessels (B). 



The Cextida are represented by the remarkable ; ' Venus' s Girdle" (Cestus 

 i-eneri-f), a band-shaped Ctenophore (Fig. 170) which sometimes attains a length 



B 



FIG. 170.- CestUS veneris. A, adult ; B, young. I. t. lateral tentacles ; mth. mouth ; s. pi. 1 , 

 s. p(.~ swimming-plates ; t. tentacle. (After Chun.) 



of 1^ metre, or nearly five feet. The body is greatly elongated horizontally in the 

 vertical, and compressed in the transverse plane, so as to have the form of a 

 ribbon, which progresses by undulations of the whole body as well as by the 

 action of its swimming-plates. Four of the swimming -plates ('. 7*/. 1 ) are very 



