TBNTACULATA. 207 



and to digest them. Although the average size is small, some of 

 them, as Cestiis, Em-liarix, reach the length of a foot. 



Order 1. TENTACULATA. 

 Ctenoplwra with tentacles. 



Section 1. Cydippidae. 



Spherical or cylindrical Ctenophora, ivith two simple or pinnate tentacles, 

 retractile into a sheath. The meridional and paragastric vessels end 'blindly. 



Fum. 1. Mertensidae. Body compressed in the stomachal-plane ; sub- 

 tentacular ribs longer than the sub-stomachal. No wing-like appendages at 

 the sensory pole. Euchlora Chun (ffaeckelia Car. and Gerst., Owenia Koll., 

 Mcrtensia Geg.) ; Charistephane Chun. 



Fam. 2. Callianiridae. Body compressed in the stomach-plane ; sub- 

 tentacular ribs longer than the sub-stomachal. Wing-like appendages at the 

 sensory pole. Callianira Peron (Fig. 165). 



Fam. 3. Pleurobrachiadae. Body round in section. Sub-tentacular and 

 sub-stomachal ribs equal in length. Hormiphora L. Ag. (Cijdippc Geg.); 

 Pleurobrachia Fleming ; Lampctia Chun ; Euplukamis Chun. 



Section 2. Lobatae. 



Body late-rally compressed ; stomach-axis longer than the funnel-axis. With 

 two lateral lobes in the oral region, and four auricles. Lateral tentacles lie in 

 a tentacular furrow ; tentacle- sheath absent. 



The auricles are provided with swimming plates, and are placed at the end 

 of the sub-tentacular ribs. The central nervous system is sunk in a pit. The 

 stomachal ribs are longer than the sub-tentacular. Mouth-opening wide, and 

 extending into a buccal furrow reaching to the base of the lobes. The four 

 interradial vessels arise direct from the funnel. The meridional vessels are con- 

 tinued on to the lobes in a sinuous course, and anastomose. The larvae are 

 Mcrtensia-like forms which, in Eueharis, become sexually mature, and reproduce 

 themselves. 



Fam. 1. Lesueuridae. Lobes and lobe-windings of vessels rudimentary. 

 Auricles long and ribbon-shaped. Lesueuria M.-Edw. 



Fam. 2. Bolinidae. Lobes of medium size. Lobe-windings of vessels simple. 

 Adradial vessels pass directly into the aboral ends of the meridional vessels. 

 Auricles short. Bolina Mertens ; BoHnopsis L. Ag. ; Hapalia Esch. 



Fam. 3. Deiopeidae. Body strongly compressed. Lobes of medium size. 

 Windings of lobe-vessels more complicated than in the Bolinidae. Auricle short. 

 Ribs consist of few but enormous plates. Sub-tentacular vessels possess short 

 aboral blind processes. Delopca Chun. 



Fam. 4. Eurhamphaeidae. Two aliform processes in the tentacular-plane at 

 the aboral pole, on which the sub-tentacular ribs are continued. Eurhamphaea 

 Gegenb. 



Fam. 5. Eucharidae. Lobes of considerable size, with complicated vessel- 

 windings. Auricles vermiform. Body beset with papillae. Aboral blind ends 

 of sub-tentacular vessels long. A long main tentacular fibre as well as the 

 lateral tentacular fibres. Eucharis Esch. 



Fam. 6. Mnemiidae. Lobes very large. Origin of auricles and lobes placed 

 almost at the same height as the funnel. Auricles long and ribbon-shaped. 

 Mncmia Esch.; Alcinoc Rang ; Mncmiopsis L. Ag. 



