CCELENTERATA. 37 



lobes [actinomeres] ; each band has a number of successive ridges 

 or plates, to each of which a row of cilia is attached. The lateral 

 actinomeres contain each a sac, which gives rise to the tentacles 

 when present. 



In this class occurs a well-marked sense-organ [ctenocyst], ovate 

 or spherical, occupying a central position, which " would seem to 

 be the localized recipient of those obscure general impressions to 

 which its lowly-organized possessor is capable of responding." 

 [Greene.] 



Reproduction is by ova, which are expelled by the mouth, 

 and the young are gradually developed, few having a larval stage. 

 The homologies between this class and the larval echinoderms 

 have led to the suggestion of their being united. 



The species vary considerably in size and shape. They are all 

 oceanic and of a very delicate texture, leaving only a mere film 

 when dried in the sun ; they are said, however, to be very voracious, 

 and to have a powerful digestion. 



With two oral lobes LOBATMS. 



Without oval lobes. 



Body ribbon-shaped TJENIAT^E. 



Body oval or round. 



With two filiform tentacles SACCATJE. 



Without tentacles . EURYSTOMATA. 



Order I. LOBAT^E. 



Body with two oral lobes. Tentacles various, turned towards 

 the mouth or wanting. ' 



The lobes project from the antero-posterior regions of the body, 

 sometimes so as to conceal the mouth. The two lateral actino- 

 meres generally terminate in a slender appendage or tentacle. 

 Eurhamphaeidae have no tentacles. 



According to Agassiz, Sicyosoma is the larval form of a Cesium. 



Eurhamphceidce. Mnemiidce. Calymfrrddcs. 



Eurhamphaea. Mnemia. Calymma. 



Lesueuria. 



Bolinida. Chiajea. 



Bolina. Ocyroe. 



Sicyosoma. 



