220 



ZOOLOGY 



SECT. 



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

 by the presence of a pair of large lappets (Fig. 1 70, A, lp.), into which the oral 

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

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



FIG. 170. Deiopea kaloknenota. A, adult ; B, young, aur. auricle ; lp. lappet ; I. t. 

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



called auricles (aur.}, which bear swimming-plates. The meridional canals 

 communicate with the stomodseal canals, and from the connecting vessels 

 curiously coiled vessels (mrd. c.) are given off into the lappets. 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 (It.). 

 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 Cestida are represented by the remarkable " Venus's Girdle ' : (Cestus 

 veneris), a band-shaped Ctenophore (Fig. 171) which sometimes attains a length 

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

 the sagittal, and compressed in the lateral plane, so as to have the form of a 

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



FIG. 171. Cestus veneris. A, adult ; B, young. 1. t. lateral tentacles ; mth. mouth ; 

 s. pi*-., s. pi 2 , swimming-plates ; t. tentacle. (After Chun.) 



action of its swimming-plates. Four of the swimming-plates (s.pl 1 .) are very 

 small; the other four (s.pl*.) are continued all along the aboral edge of the 

 body. The bases of the two principal tentacles (t.) are large and are enclosed 

 in sheaths, and, as in Lobata, numerous small lateral tentacles (It.) spring 

 from grooves which, in the present case, are continued the whole length of the 



