C(ELENTEKATA. 



23 



From the centre hangs a tubular body the manubrium con- 

 taining the body-cavity, and acting as a polypite. The body- 

 cavity is connected with four or more canals radiating to the 

 circumference, and giving rise with their branches to a circular 

 canal. Nervous filaments with ganglionic enlargements running 

 round the margin have been found in many genera. Pigment- 

 spots (ocelli), black, vermilion, or carmine, are imbedded in the 

 marginal ectoderm. Small corpuscles containing mineral con- 

 cretions, and known as " lithocysts," are supposed to represent 

 auditory organs. 



The classification is unusually difficult, owing to the association 

 of similar trophosomes with dissimilar gonosomes, and vice versa. 

 The planoblast also, at its liberation, is in an immature state, 

 and the adult condition is therefore uncertain. In 1864 Allman 

 divided this order into nine families ; Carus, the previous year, 

 recognized only two ; Hincks, in 1868, had twelve ; and in 1871 

 Allman made twenty-one ; eleven of these had only one genus, 

 and mostly only one species in each : they are enumerated below. 

 Schmarda has eight, and Glaus ten families, including Hydridce. 



Clavidce. BougainvillUdce. Myriothelida. 



Clava. Bougainvillia. Myriothela. 



Cordylophora. 



Clavatellidce. 

 Clavatella. 



Corymorphidee. 

 Corymorpha. 

 Amalthfea. 



MonoeaulidcB. 

 Monocaulus. 



Tubulariidee. 

 Tubularia. 



Hybocodonida. 

 Hybocodon. 



Hydrolaridce. 

 Lar. 



Turns. 



Corynida. 

 Coryne. 



Bougainvillia. 

 Perigonimus. 



Eudendriidas. 

 Eudendrium. 



Hydractiniida. 

 Hydractinia. 



Podocorynida. 

 Podocoryne. 



Syncoryne. 

 Gemmaria. 



Cladonema. 



Dicorynida. 

 Dicoryne. 



Nemopsis. 



Pennariida. 



Bimeriida. Pennaria. 



Bimeria. 



Wrightia=Atractylis. Cladocorymda. 

 Hydranthea. Cladocoryne. 



