CCELENTERA.TA. 39 



The following group is made a subclass of Hydrozoa by Nichol- 

 son, a suborder of Hydroida by Allraan, while Carus (1875) 

 places it with the Polyzoa, as one of the four " orders " of 

 Gymnolasmata. It is Von Hayek's sixth order of Hydroida ; but 

 is placed as a pendant to the Alcyonaria by Schmarda. It is not 

 noticed by Claus. 



KHABDOPHOEA. 

 GRAPTOLITHINA. 



" Hydrosoma compound, occasionally branched, consisting of 

 numerous polypites united by a ccenosarc, the latter being included 

 in a strong, tubular polypary, whilst the former were protected 

 by hydrothecae." (Nicholson.) 



These are Palaeozoic organisms, generally known as " Grapto- 

 lites," whose structure is still far from being entirely understood. 

 They " are usually found as glistening, pyritous impressions, with 

 a silvery lustre. In some cases, however, they are found in re- 

 lief." The genera are numerous. 



*Monograpsus. 

 *Diplograpsus. 

 *Rhabdopleura. 



